Device and method for assisting selection of surgical staple height

ABSTRACT

A surgical instrument for assessing a mechanical property of tissue under compression is disclosed herein comprising a handle; an elongated shaft distally disposed to the handle; an end effector distally disposed to the elongated shaft and comprising a first and a second jaw member pivotally engaged with each other to open and close when operated by the handle; a force gauge assembly comprising a compression head and a force transducer; an adjustable spacer assembly disposed on the first jaw member proximally to the force gauge assembly and comprising an adjustable spacer member and a spacer base; a control mechanism supported by the elongated shaft and disposed adjacent to the handle for producing an actuation force for controlling the adjustable spacer assembly; and at least one control link operably coupled with the control mechanism and the spacer base, and configured to transmit the actuation force.

CROSS REFERENCE TO RELATED APPLICATIONS

The present application claims the benefit of and priority to U.S.Provisional Patent Applications No. 62/912,659, filed on Oct. 9, 2019and No. 62/971,161, filed on Feb. 6, 2020, the entire contents of whichare incorporated by reference herein.

The present application is related to U.S. patent application Ser. No.16/932,873, filed on Jul. 20, 2020, U.S. patent application Ser. No.16/932,876, filed on Jul. 20, 2020 and U.S. patent application Ser. No.16/852,464, filed on Apr. 18, 2020, which is a Continuation applicationof U.S. patent application Ser. No. 15/893,638, filed on Feb. 11, 2018,now U.S. Pat. No. 10,682,139, issued on Jun. 16, 2020, the entirecontents of which are incorporated by reference herein.

TECHNICAL FIELD

The present invention relates to a medical device and method for use insurgical procedures. More particularly, the present invention relates toa surgical device and method for assisting selection of surgical stapleheight in a surgical stapling operation.

BACKGROUND OF THE INVENTION

The utilization of mechanical tissue fastening instruments, notably,open and endoscopic surgical staplers have been increasing steadily inrecent years as a substitute for suturing in joining a tissue, joiningand cutting a tissue simultaneously and performing anastomosis oftubular organs belonging to the digestive system in a number of surgicaldisciplines. Over the years these instruments have proven to providesignificant clinical benefits of improved patient outcome in addition toprocedural benefits of reduced procedure time and simplified surgicaltasks when compared to laborious and time consuming suturing, andrelated cost savings. In certain types of surgical procedures use ofsurgical staplers has become the preferred method of joining a tissueincluding the bariatric, thoracic and colorectal surgeries.

There are several known types of surgical stapler instrumentsspecifically adapted for use in various procedures such as end-to-endanastomosis, gastrointestinal anastomosis, endoscopic gastrointestinalanastomosis, and transverse anastomosis. Examples of stapler instrumentsfor these various procedures can be found in U.S. Pat. Nos. 5,915,616;6,202,914; 5,865,361; and 5,964,394, which are each herein incorporatedby reference.

Known endoscopic surgical stapler instruments comprise a handle and anend effector that are fixedly attached to either ends of an elongateshaft and operatively engaged with each other. An end effectorsimultaneously makes a longitudinal incision in tissue and applies linesof staples on opposing sides of the incision. An end effector includes apair of opposed jaw members that, if the instrument is intended forendoscopic or laparoscopic applications, are capable of passing througha cannula passageway. One of the jaw members, often referred to as acartridge jaw member, receives a staple cartridge having at least twolaterally spaced rows of staples in an elongate cartridge channel or acartridge bay. The other jaw member, often referred to as an anvil jawmember, defines an anvil having staple-forming pockets aligned with therows of staples in the staple cartridge. The instrument commonlyincludes a plurality of reciprocating wedges which, when drivendistally, pass through openings in the staple cartridge and engagedrivers supporting the staples to effect the firing of the staplestoward the anvil.

In surgical stapling operation a physician operator first positions theend effector of a surgical stapler instrument to capture a target tissuebetween the two jaw members in open position and then operates thehandle to close the two jaw members to clamp and compress the targettissue to a nominal thickness defined by the gap distance between thetissue contacting surfaces of the staple cartridge and the anvil priorto the firing of the staples. In the designs of presently availablestapler instruments a physician has no means to control the degree orforce of target tissue compression but is presented with a set ofstandardized staple cartridges colored coded according to the formedheight(s) of staples contained therein, which correlates with the gapdistance between the tissue contacting surfaces of the staple cartridgeand anvil. Presently, the standardized set of staple cartridges,typically color coded white, blue, gold, green and black in theascending order of staple heights contained therein, includes stapleswith formed heights between 1 mm and 2.3 mm in discrete increment. Thereare also in the market a set of staple cartridges, each cartridgecontaining a combination staples of varying heights with its own uniquecolor coding tailored for application on tissue with varying compressedthickness. In compressing the target tissue the two jaw memberscomprising the end effector of stapler instrument are subject to adistributed reactionary load from the compressed tissue usuallyresulting in deflection of the two jaw members increasing progressivelyalong the length thereof going from the proximal to distal end and moreso, in the anvil than in the cartridge jaw member which is moresubstantial and structurally rigid. The corresponding variation in thegap distance between the tissue contacting surfaces of the staplecartridge and the anvil makes the tissue compression non-uniformdecreasing progressively going from the proximal to distal ends of theend effector.

The level of tissue compression is one of the key factors that determinesuccess of a surgical stapling operation often defined by adequatehemostasis and minimal damage of tissue along the staple line, andleak-free sealing of the target tubular organ among otherconsiderations. It is known that a desirable clinical outcome of asurgical stapling operation is most likely achieved when the targettissue is compressed to a compression force between 6 g/mm² or 8 g/mm².Since present surgical stapler technology does not provide means tocontrol the compression force of the target tissue a physician needs tochoose a staple cartridge out of a standard set that would bestapproximate the optimal compression force for the target tissue when thetwo jaw members are closed with the chosen staple cartridge mounted inthe cartridge bay. Having no practical means to help direct selection ofstaple cartridge, for example, accessory tools to directly assess a keymechanical property or condition of the target tissue, a physician isleft to rely solely on his or her experience, or educated guess inselecting a staple cartridge, which leaves open possibility of under- orover-compression of the target tissue. Under-compression of tissue couldlead to inadequate hemostasis and potential leakage of content containedwithin the tissue while over-compression to tearing of tissue orischemia requiring prolonged period of healing. The staple cartridgeselection is particularly difficult for a target tissue belonging to anorgan with naturally occurring, large thickness variation such as in thestomach or an organ with unknown variation in mechanical properties suchas in the lung at different disease state.

Manufacturers of present surgical stapler instruments instruct aphysician to verify the adequacy of selected staple cartridge incompressing a target tissue by the feedback force felt in the handoperating the handle of the stapler instrument to apply the tissuecompression. The instructions basically say to switch to a new staplecartridge with staples of larger formed height if it is overly difficultto operate the handle to apply compression to the target tissuespecifically to guard against over-compression. This method is proven tobe hardly practical in the field because the feedback force felt in thepalm of the physician's hand may not necessarily correlates with thelevel of tissue compression due to the facts that the feedback force maybe distorted being passed down through mechanical linkages and jointscomprising the operating mechanism for the end effector and that the twojaw members comprising the end effector undergoes deflection caused bythe reactionary load from the compressed tissue. In addition a unit ofchange in the compressed tissue thickness represented by the standardset of staple cartridges typically corresponds to only around few tensof gram of force in tissue compression which is barely discernible bythe haptic sense felt in the palm of the hand alone even under the bestof circumstances. Corresponding instruction for staple cartridgeselection for preventing under-compression of a target tissue does noteven exist.

U.S. Pat. No. 8,893,946 to Boudreaux et al., which is hereinincorporated by reference, describes a surgical instrument that includescomponents for measuring the thickness of a tissue clamped between thetwo jaw members of an end effector thereof relying on a strain gauge orstrain gauges as a means to generate a signal or signals correspondingto the tissue thickness and/or a compression load applied to the tissue.This disclosure describes the strain gauges as being used stand-alonebut fails to describe how the strain gauges are practically implemented,for example, in the form of a load cell, well known to those of skill inthe art, to generate such signals that could be converted to thethickness of tissue or the compression load acting thereon. The surgicalinstrument in this disclosure does not include any means to prevent orcompensate for the potential deflection of a jaw member comprising anend effector as a result of a reactionary load from the compressedtissue nor for the effect of the play present in the closure mechanismof the two jaw members comprising the end effector on the tissuethickness measurement. This disclosure also fails to define thethickness of the clamped tissue in such sufficient detail for it to beof practical use in the selection of a staple cartridge for a staplingoperation on the tissue.

Therefore, significant needs exist for a surgical device and method thatwould aid a physician in selecting a staple cartridge from the standardset of staple cartridges.

BRIEF SUMMARY OF THE INVENTION

The present invention is directed toward a surgical device and methodfor use in surgical procedures. More particularly, the present inventionrelates to a surgical device and method for assisting selection of astaple cartridge from the standard set of staple cartridges optimal fora target tissue of a surgical stapling operation.

To address the foregoing needs and with other objects in view there areprovided, in accordance with the present invention, a surgical devicefor enabling a surgical stapler instrument to compress a tissueconsistently to a predetermined thickness and measure a reactionary loadtherefrom and a method for assisting a physician in selecting a staplecartridge optimal for a tissue of a surgical stapling operation.

Ina preferred embodiment of the present invention, a compression gaugecartridge for use mounted in a cartridge bay of a cartridge jaw membercomprising an end effector, together with an anvil jaw member having atissue contacting surface, of a surgical stapler instrument to compressa tissue consistently to a predetermined thickness and measure areactionary load therefrom for assisting selection of a staple cartridgeand assessing the condition of the tissue comprises: a cartridge bodyhaving a proximal end and a distal end, and a tissue supporting surface,wherein said cartridge body is configured for said compression gaugecartridge to be releasably mounted in said cartridge bay and for saidtissue supporting surface to be at least at a predetermined distancefrom said tissue contacting surface of said anvil jaw member when saidcartridge jaw member and said anvil jaw member are in a fully closedposition; a force gauge assembly comprising a force transducer and acompression head having a tissue compression face, wherein said forcegauge assembly is supported by said cartridge body positioned betweensaid proximal end and said distal end thereof and wherein saidcompression head is configured and disposed so that said tissuecompression face thereof lies substantially closer to said tissuecontacting surface of said anvil jaw member than said tissue supportingsurface of said cartridge body; and a spacer member extending from saidtissue supporting surface of said cartridge body, wherein saidcompression head comprising said force gauge assembly is positioneddistally with respect to said spacer member. In an alternate embodimentsaid tissue supporting surface of said cartridge body may be contouredin such a way to further reduce compression of said tissue disposedbetween said tissue supporting surface and said tissue contactingsurface when said cartridge jaw member and said anvil jaw member are ina fully closed position.

In an alternate embodiment of the present invention, a compression gaugecartridge for use mounted in a cartridge bay of a cartridge jaw membercomprising an end effector, together with an anvil jaw member having atissue contacting surface, of a surgical stapler instrument to compressa tissue so that said cartridge jaw member and said anvil jaw membercome to a predetermined angular positional relationship with each otherand measure a reactionary load therefrom for assisting selection of astaple cartridge comprises: a cartridge body having a proximal end and adistal end, and a tissue supporting surface, wherein said cartridge bodyis configured for said compression gauge cartridge to be releasablymounted in said cartridge bay and for said tissue supporting surface tobe at least at a predetermined distance from said tissue contactingsurface of said anvil jaw member when said cartridge jaw member and saidanvil jaw member are in a fully closed position; and a force gaugeassembly comprising a force transducer and a compression head having atissue compression face, wherein said force gauge assembly is supportedby said cartridge body positioned between said proximal end and saiddistal end thereof and wherein said compression head is configured anddisposed so that said tissue compression face thereof lies substantiallycloser to said tissue contacting surface of said anvil jaw member thansaid tissue supporting surface of said cartridge body. In an alternateembodiment said tissue supporting surface of said cartridge body may becontoured in such a way to further reduce compression of said tissuedisposed between said tissue supporting surface and said tissuecontacting surface when said cartridge jaw member and said anvil jawmember are in a fully closed position.

In an embodiment of the present invention, a surgical stapler instrumentmay further include a spacer block of a predetermined height disposed ata handle comprising said surgical stapler instrument for defining apredetermined extent said handle may be operated to close a cartridgejaw member and an anvil jaw member comprising an end effector comprisingsaid surgical stapler instrument so that said cartridge jaw member andsaid anvil jaw member come to a predetermined angular positionalrelationship with each other.

In a preferred embodiment of the present invention, a surgicalcompression gauge instrument for compressing a tissue consistently to apredetermined thickness and measuring a reactionary load therefrom forassisting selection of a staple cartridge and assessing the condition ofthe tissue comprises: a handle portion; a body portion extendingdistally from said handle portion and defining a longitudinal axis; anda tool assembly disposed at a distal end of and operatively connected tosaid body portion, and comprising a compression gauge jaw member havinga proximal end and a distal end and a tissue supporting surface, and ananvil jaw member having a tissue contacting surface, wherein saidcompression gauge jaw member is configured for said tissue supportingsurface thereof to be at least at a predetermined distance from saidtissue contacting surface of said anvil jaw member when said compressiongauge jaw member and said anvil jaw member are in a fully closedposition, and configured to open and close when operated by said handleportion, wherein said compression gauge jaw member comprises a forcegauge assembly, supported therein and positioned between said proximalend and said distal end thereof, comprising a force transducer and acompression head having a tissue compression face, wherein saidcompression head is configured and disposed so that said tissuecompression face thereof lies substantially closer to said tissuecontacting surface of said anvil jaw member than said tissue supportingsurface of said compression gauge jaw member; and a spacer memberextending from said tissue supporting surface of said compression gaugejaw member, wherein said compression head comprising said force gaugeassembly is positioned distally with respect to said spacer member.

In a preferred embodiment of the present invention, a method forselecting a staple cartridge from the standard set of staple cartridges,each containing staples of a predetermined height, optimal for a tissueof a surgical stapling operation comprises steps of: mounting acompression gauge cartridge of the present invention in a cartridge bayof a cartridge jaw member comprising an end effector, together with ananvil jaw member, of a surgical stapler instrument, a spacer member ofwhich is configured to consistently provide a gap distance,corresponding to a height of staples contained in a predeterminedcartridge from the set of standard staple cartridges, between a tissuecompression face of a compression head comprising a force gauge assemblycomprising said compression gauge cartridge and a tissue contactingsurface of said anvil jaw member; capturing a tissue between saidcartridge jaw member and said anvil jaw member; closing said cartridgejaw member and said anvil jaw member to compress said tissue capturedbetween said tissue compression face and said tissue contacting surfaceto a predetermined thickness corresponding to said gap distancethere-between; reading out a reactionary load from said compressedtissue displayed on a force transducer indicator; comparing saidreactionary load reading with a value known to be optimal for a staplingoperation of said tissue to determine if said reactionary load is case(1) within, case (2) below or case (3) above a window of a predeterminedwidth around said optimal value and how large a size of difference is incases (2) and (3); selecting a staple cartridge from the standard set ofstaple cartridges containing staples of a height corresponding to saidpredetermined thickness of said compressed tissue if the result ofcomparison is case (1), or a staple cartridge containing staples of aheight smaller than said predetermined thickness of said compressedtissue taking into account said size of difference if the result ofcomparison is case (2), or a staple cartridge containing staples of aheight larger than said predetermined thickness of said compressedtissue taking into account said size of difference if the result ofcomparison is case (3). In an alternate embodiment, a method forselecting a staple cartridge from the standard set of staple cartridges,each containing staples of a predetermined height, optimal for a tissueof a surgical stapling operation may further comprise a step of waitingfor a predetermined length of time after closing said cartridge jawmember and said anvil jaw member to compress said tissue.

In an alternate embodiment of the present invention, a method forselecting a staple cartridge from the standard set of staple cartridges,each containing staples of a predetermined average height, optimal for atissue of a surgical stapling operation comprises steps of: mounting acompression gauge cartridge of the present invention in a cartridge bayof a cartridge jaw member comprising an end effector, together with ananvil jaw member, of a surgical stapler instrument, a spacer member ofwhich is configured to consistently provide a gap distance,corresponding to an average height of staples contained in apredetermined cartridge from the set of standard staple cartridges,between a tissue compression face of a compression head comprising aforce gauge assembly comprising said compression gauge cartridge and atissue contacting surface of said anvil jaw member; capturing a tissuebetween said cartridge jaw member and said anvil jaw member; closingsaid cartridge jaw member and said anvil jaw member to compress saidtissue captured between said tissue compression face and said tissuecontacting surface to a predetermined thickness corresponding to saidgap distance there-between; reading out a reactionary load from saidcompressed tissue displayed on a force transducer indicator; comparingsaid reactionary load reading with a value known to be optimal for astapling operation of said tissue to determine if said reactionary loadis case (1) within, case (2) below or case (3) above a window of apredetermined width around said optimal value and how large a size ofdifference is in cases (2) and (3); selecting a staple cartridge fromsaid standard set of staple cartridges containing staples of an averageheight corresponding to said predetermined thickness of said compressedtissue if the result of comparison is case (1), or a staple cartridgecontaining staples of an average height smaller than said predeterminedthickness of said compressed tissue taking into account said size ofdifference if the result of comparison is case (2), or a staplecartridge containing staples of an average height larger than saidpredetermined thickness of said compressed tissue taking into accountsaid size of difference if the result of comparison is case (3). In analternate embodiment, a method for selecting a staple cartridge from thestandard set of staple cartridges, each containing staples of apredetermined average height, optimal for a tissue of a surgicalstapling operation may further comprise a step of waiting for apredetermined length of time after closing said cartridge jaw member andsaid anvil jaw member to compress said tissue.

In another alternate embodiment of the present invention, a method forselecting a staple cartridge from the standard set of staple cartridges,each containing staples of a predetermined height, optimal for a tissueof a surgical stapling operation comprises steps of: mounting acompression gauge cartridge of the present invention in a cartridge bayof a cartridge jaw member comprising an end effector, together with ananvil jaw member, of a surgical stapler instrument, a spacer member ofwhich is configured to consistently provide a gap distance,corresponding to a height of staples contained in a green cartridge fromthe set of standard staple cartridges, between a tissue compression faceof a compression head comprising a force gauge assembly comprising saidcompression gauge cartridge and a tissue contacting surface of saidanvil jaw member; capturing a tissue between said cartridge jaw memberand said anvil jaw member; closing said cartridge jaw member and saidanvil jaw member to compress said tissue captured between said tissuecompression face and said tissue contacting surface to a predeterminedthickness corresponding to said gap distance there-between; reading outa reactionary load from said compressed tissue displayed on a forcetransducer indicator; comparing said reactionary load reading with avalue known to be optimal for a stapling operation of said tissue todetermine if said reactionary load is case (1) within, case (2) below orcase (3) above a window of a predetermined width around said optimalvalue; selecting a green cartridge from the standard set of staplecartridges if the result of comparison is case (1) or a blue cartridgeif the result of comparison is case (2), or a black cartridge if theresult of comparison is case (3). In an alternate embodiment, a methodfor selecting a staple cartridge from the standard set of staplecartridges, each containing staples of a predetermined height, optimalfor a tissue of a surgical stapling operation may further comprise astep of waiting for a predetermined length of time after closing saidcartridge jaw member and said anvil jaw member to compress said tissue.

In an alternate embodiment of the present invention, a method forselecting a staple cartridge from the standard set of staple cartridges,each containing staples of a predetermined height, optimal for a tissueof a surgical stapling operation comprises steps of: mounting acompression gauge cartridge of the present invention in a cartridge bayof a cartridge jaw member comprising an end effector, together with ananvil jaw member, of a surgical stapler instrument, a spacer member ofwhich is configured to consistently provide a gap distance between atissue compression face of a compression head comprising a force gaugeassembly comprising said compression gauge cartridge and a tissuecontacting surface of said anvil jaw member; capturing a tissue betweensaid cartridge jaw member and said anvil jaw member; closing saidcartridge jaw member and said anvil jaw member to compress said tissuecaptured between said tissue compression face and said tissue contactingsurface to a predetermined thickness corresponding to said gap distancethere-between; reading out a reactionary load from said compressedtissue displayed on a force transducer indicator; providing a referencetissue for which an optimal staple height for a surgical staplingoperation is known; comparing said reactionary load reading with areactionary load from said reference tissue compressed to saidpredetermined thickness over the same area of said reference tissue asthat of said tissue compression face of said compression head todetermine if said reactionary load is case (1) within, case (2) below orcase (3) above a window of a predetermined width around said reactionaryload from said reference tissue and how large a size of difference is incases (2) and (3); selecting a staple cartridge from the standard set ofstaple cartridges containing staples of a height known to be optimal forsaid reference tissue if the result of comparison is case (1), or astaple cartridge containing staples of a height smaller than that ofstaples known to be optimal for said reference tissue taking intoaccount said size of difference if the result of comparison is case (2),or a staple cartridge containing staples of a height larger than that ofstaples known to be optimal for said reference tissue taking intoaccount said size of difference if the result of comparison is case (3).In an alternate embodiment, a method for selecting a staple cartridgefrom the standard set of staple cartridges, each containing staples of apredetermined height, optimal for a tissue of a surgical staplingoperation may further comprise a step of waiting for a predeterminedlength of time after closing said cartridge jaw member and said anviljaw member to compress said tissue.

In an alternate embodiment of the present invention, a method forselecting a staple cartridge from the standard set of staple cartridges,each containing staples of a predetermined height, optimal for a tissueof a surgical stapling operation comprises steps of: mounting acompression gauge cartridge of the present invention in a cartridge bayof a cartridge jaw member comprising an end effector, together with ananvil jaw member having a tissue contacting surface, of a surgicalstapler instrument; capturing a tissue between said cartridge jaw memberand said anvil jaw member; closing said cartridge jaw member and saidanvil jaw member to compress said tissue captured there-between so thatsaid cartridge jaw member and said anvil jaw member come to apredetermined angular positional relationship with each other; readingout a reactionary load from said compressed tissue displayed on a forcetransducer indicator; providing a reference tissue for which an optimalstaple height for a surgical stapling operation is known; comparing saidreactionary load reading with a reactionary load from said referencetissue compressed so that said cartridge jaw member and said anvil jawmember come to said predetermined angular positional relationship witheach other to determine if said reactionary load is case (1) within,case (2) below or case (3) above a window of a predetermined widtharound said reactionary load from said reference tissue and how large asize of difference is in cases (2) and (3); selecting a staple cartridgefrom the standard set of staple cartridges containing staples of aheight known to be optimal for said reference tissue if the result ofcomparison is case (1), or a staple cartridge containing staples of aheight smaller than that of staples known to be optimal for saidreference tissue taking into account said size of difference if theresult of comparison is case (2), or a staple cartridge containingstaples of a height larger than that of staples known to be optimal forsaid reference tissue taking into account said size of difference if theresult of comparison is case (3). In an alternate embodiment, a methodfor selecting a staple cartridge from the standard set of staplecartridges, each containing staples of a predetermined height, optimalfor a tissue of a surgical stapling operation may further comprise astep of waiting for a predetermined length of time after closing saidcartridge jaw member and said anvil jaw member to compress said tissue.

In order to make an informed selection of a staple cartridge for atissue of a surgical stapling operation or to assess a condition of atissue in a surgery, a physician mounts a compression gauge cartridge ofthe present invention in a cartridge bay of a cartridge jaw member of asurgical stapler instrument prepared to be used for the staplingoperation or employ a dedicated surgical instrument with a toolassembly, a jaw member of which is instrumented with a compression gaugedevice including a force gauge assembly and a spacer member. Thephysician then operates the handle portion of the surgical staplerinstrument or the dedicated surgical instrument to capture a tissuebetween the two jaw members comprising the end effector or a toolassembly and close the two jaw members to compress the tissue to apredetermined thickness set by the spacer member comprising thecompression gauge cartridge or the compression gauge device. Thesurgical stapler instrument instrumented with the compression gaugecartridge and the dedicated surgical instrument instrumented with thecompression gauge device is capable of providing a predetermined gapdistance consistently and with a high degree of repeatability betweenthe tissue compression face of the compression head comprising the forcegauge assembly and the tissue contacting surface of the anvil jawmember. The compression of tissue takes place over the area covered bythe tissue compression face of the compression head, which reduces thetissue to a predetermined thickness corresponding to the predeterminedgap distance. Preferably, the predetermined thickness of the compressedtissue is the formed height of staples contained in a green staplecartridge from the standard set of staple cartridges. The compressionhead transfer a reactionary load from the compressed tissue exertedthereon to the force transducer comprising the force gauge assembly,which is displayed on a force transducer indicator connected to theforce transducer comprising the force gauge assembly. Comparing thereactionary load with a known optimal tissue compression force for asurgical stapling operation the physician may decide to choose a greenstaple cartridge or other staple cartridges, blue or black, containingstaples of a height smaller or larger than the green cartridge in thestandard set of staple cartridges. Preferably, the control program forthe force transducer indicator includes a software function forperforming the comparison of the measured reactionary load with a set ofvalues stored in the internal memory to provide a signal indicating arecommendation on the staple cartridge selection, for example, in theform of a color coded signal lights or other easily recognizable forms.

The presently disclosed compression gauge cartridge and method, togetherwith attendant advantages, will be more clearly illustrated below by thedescription of the drawings and the detailed description of theembodiments.

BRIEF DESCRIPTION OF THE DRAWINGS

The following exemplary figures are provided to supplement thedescription below and more clearly describe the invention. In thefigures, like elements are generally designated with the same referencenumeral for illustrative convenience and should not be used to limit thescope of the present invention.

FIG. 1 is a plot of a stress-strain curve of a stomach tissue accordingto an embodiment of the present invention.

FIG. 2A is a perspective view of an exemplary surgical staplerinstrument according to an embodiment of the present invention.

FIG. 2B is a perspective view of an end effector of an exemplarysurgical stapler instrument according to an embodiment of the presentinvention.

FIG. 3A is a perspective view of a compression gauge cartridge disposedin a cartridge bay of a cartridge jaw member of an end effector of anexemplary surgical stapler instrument according to an embodiment of thepresent invention.

FIG. 3B is a perspective view of a compression gauge cartridgepositioned spaced apart from a cartridge bay according to an embodimentof the present invention.

FIG. 3C is an exploded view of a compression gauge cartridge accordingto an embodiment of the present invention.

FIG. 3D is a perspective view of a compression gauge cartridge with acartridge body sectioned along the line 3D-3D shown in FIG. 3C andspaced apart according to an embodiment of the present invention.

FIG. 4A is a perspective view of a compression gauge cartridge accordingto an alternate embodiment of the present invention.

FIG. 4B is a perspective view of a compression gauge cartridge, shown inFIG. 4A, with a cartridge body sectioned similarly to that shown in FIG.3C and spaced apart according to an alternate embodiment of the presentinvention.

FIG. 5A is a perspective view of a compression gauge cartridge accordingto another alternate embodiment of the present invention.

FIG. 5B is a perspective view of a compression gauge cartridge, shown inFIG. 5A, with a cartridge body sectioned similarly to that shown in FIG.3C and spaced apart according to another alternate embodiment of thepresent invention.

FIG. 6A is a schematic, side elevation view of a tissue captured betweenan anvil jaw member and a staple cartridge comprising a cartridge jawmember in an open position according to an embodiment of the presentinvention.

FIG. 6B is a schematic, side elevation view of a tissue compressedbetween an anvil jaw member and a staple cartridge in a closed positionaccording to an embodiment of the present invention.

FIG. 6C is a perspective view of a cartridge body comprising acompression gauge cartridge according to an embodiment of the presentinvention.

FIG. 6D is a schematic, side elevation view of a tissue compressedbetween a compression gauge cartridge comprising a cartridge jaw memberand an anvil jaw member in a closed position according to an embodimentof the present invention.

FIG. 6E is a perspective view of a cartridge body comprising acompression gauge cartridge according to an alternate embodiment of thepresent invention.

FIG. 7A is a perspective view of a force gauge assembly with acompression head set spaced apart according to an embodiment of thepresent invention.

FIG. 7B is a perspective view of a compression head comprising a forcegauge assembly sectioned along a long symmetry plane and spaced apartaccording to an alternate embodiment of the present invention.

FIG. 7C is a perspective view of a signal conduction means and acartridge jaw member partially broken away according to an embodiment ofthe present invention.

FIG. 7D is a perspective view of a signal conduction means comprising acompression gauge cartridge partially broken away according to analternate embodiment of the present invention.

FIG. 8A is a perspective view of a force gauge assembly with acompression head set spaced apart therefrom according to an alternateembodiment of the present invention.

FIG. 8B is a perspective view of a compression head comprising a forcegauge assembly sectioned along a long symmetry plane and spaced apartaccording to an another alternate embodiment of the present invention.

FIG. 8C is a perspective view of a cantilevered compression headcomprising a force gauge assembly disposed in a cartridge body shownpartially broken away, sectioned along a symmetry plane and spaced apartaccording to an another alternate embodiment of the present invention.

FIG. 8D is a perspective view of a deformable compression headcomprising a force gauge assembly disposed in a cartridge body shownpartially broken away, sectioned along a symmetry plane and spaced apartaccording to an another alternate embodiment of the present invention.

FIG. 9A is a perspective view of a force gauge assembly with acompression head set spaced apart therefrom according to anotheralternate embodiment of the present invention.

FIG. 9B is a perspective view of a compression head comprising a forcegauge assembly sectioned along a symmetry plane and spaced apartaccording to an another alternate embodiment of the present invention.

FIGS. 10A and 10B are side elevation views of a compression gaugecartridge comprising a cartridge jaw member and an anvil jaw memberaccording to embodiments of the present invention.

FIG. 11A is a perspective view of a cartridge body and a repositionablespacer member comprising a compression gauge cartridge according to anembodiment of the present invention.

FIGS. 11B and 11C are perspective views of a spacer member with anextension member according to embodiments of the present invention.

FIG. 11D is a perspective view of a protective cover disposed on acartridge body comprising a compression gauge cartridge according to anembodiment of the present invention.

FIGS. 12A-12C are perspective views of a cartridge body and a cartridgebay, partially broken away and sectioned and spaced apart, and anadjustable spacer member comprising a compression gauge cartridgeaccording to various embodiments of the present invention.

FIGS. 12D and 12E are perspective views of a cartridge body and acartridge bay, partially broken away and sectioned and spaced apart, anda rotatable spacer member comprising a compression gauge cartridgeaccording to an alternate embodiment of the present invention.

FIG. 13A is a schematic, side elevation view of a reference block, acompression gauge cartridge and an anvil jaw member according to anembodiment of the present invention.

FIG. 13B is a perspective view of a protective cover disposed on acartridge body according to an embodiment of the present invention.

FIG. 13C is a perspective view of a cartridge body, a protective coverand a cartridge bay, partially broken away and sectioned and spacedapart, and an adjustable spacer member biased by a spring according toan embodiment of the present invention.

FIG. 14 is an assembly view of a compression gauge cartridge comprisingtwo parts according to an alternate embodiment of the present invention.

FIG. 15 is a perspective view of a surgical compression gauge instrumentcomprising a compression gauge jaw member according to an embodiment ofthe present invention.

FIG. 16 is a perspective view of a compression gauge cartridge accordingto an alternate embodiment of the present invention.

FIG. 17 is a side elevation view of a compression gauge cartridgecomprising a cartridge jaw member and an anvil jaw member according toembodiments of the present invention.

FIG. 18 is a perspective view of a surgical stapler instrument accordingto an embodiment of the present invention.

FIG. 19 is a perspective view of a compression gauge cartridge accordingto an alternate embodiment of the present invention.

FIG. 20 is a perspective view of a compression gauge cartridge with acartridge body sectioned similarly to that shown in FIG. 3C and spacedapart according to an alternate embodiment of the present invention.

FIG. 21 is a perspective view of a cartridge body, partially brokenaway, and sectioned and spaced apart, and a spacer assembly according toan embodiment of the present invention.

FIG. 22A is a perspective view of a spacer assembly with the stopper inthe path of the spacer member according to an embodiment of the presentinvention.

FIG. 22B is a perspective view of a spacer assembly with the stopper outof the path of the spacer member according to an embodiment of thepresent invention.

FIG. 23A is a perspective view of a stopper comprising a plurality ofsteps joined with a stopper control link according to an embodiment ofthe present invention.

FIG. 23B is a perspective view of a spacer member held in positionresting at a step of a stopper comprising a plurality of steps joinedwith a stopper control link according to an embodiment of the presentinvention.

FIG. 23C is a perspective view of a spacer member with a stopper,comprising a plurality of steps joined with a stopper control link, outof the path thereof according to an embodiment of the present invention.

FIG. 24 is a perspective view of a stopper comprising a sloped facejoined with a stopper control link according to an embodiment of thepresent invention.

FIG. 25 is a perspective view of a cartridge body, partially brokenaway, and sectioned and spaced apart, and a spacer assembly according toan embodiment of the present invention.

FIG. 26A is a perspective view of a spacer assembly with the stopper inthe path of the spacer member according to an embodiment of the presentinvention.

FIG. 26B is a perspective view of a spacer assembly with the stopper outof the path of the spacer member according to an embodiment of thepresent invention.

FIG. 27 is a perspective view of a cartridge body, partially brokenaway, and sectioned and spaced apart, and a plurality of spacerassemblies according to an embodiment of the present invention.

FIGS. 28A-28C are perspective views of a plurality of spacer assembliesaccording to an embodiment of the present invention.

FIG. 29 is a perspective view of a cartridge body, partially brokenaway, and sectioned and spaced apart, and a spacer assembly according toan embodiment of the present invention.

FIG. 30 is an exploded view of a spacer assembly according to anembodiment of the present invention.

FIGS. 31A-31C are perspective views of a spacer assembly according to anembodiment of the present invention.

FIG. 32 is a perspective view of a cartridge body, partially brokenaway, and sectioned and spaced apart, and a gap sensor according to anembodiment of the present invention.

FIG. 33 is an exploded view of a gap sensor according to an embodimentof the present invention.

FIG. 34 is a perspective view of a piston comprising a gap sensorsectioned apart according to an embodiment of the present invention.

FIG. 35 is a perspective view of a cartridge body, partially brokenaway, and sectioned and spaced apart, and a gap sensor according to anembodiment of the present invention.

FIG. 36 is a perspective view of a gap sensor according to an embodimentof the present invention.

FIG. 37 is a perspective view of a cartridge body, partially brokenaway, and sectioned and spaced apart, and a gap sensor according to anembodiment of the present invention.

FIG. 38 is a perspective view of a gap sensor according to an embodimentof the present invention.

FIG. 39 is a perspective view of a cartridge body, partially brokenaway, and sectioned and spaced apart, and a gap sensor according to anembodiment of the present invention.

FIG. 40 is an exploded view of a gap sensor according to an embodimentof the present invention.

FIGS. 41-44 is a side elevation view of a compression gauge cartridgeand an anvil jaw member comprising an end effector of a surgical staplerinstrument instrumented with the compression gauge cartridge accordingto an embodiment of the present invention.

FIGS. 45A and 45B is a perspective view of a cartridge body partiallybroken away and partially broken away, sectioned and spaced apart,respectively, and a gap sensor according to an embodiment of the presentinvention.

FIG. 46 is a perspective view of a gap sensor according to an embodimentof the present invention.

FIG. 47 is a perspective view of a surgical instrument according to anembodiment of the present invention.

FIG. 48 is a perspective view of a surgical instrument, shown in FIG.47, partially sectioned apart according to an embodiment of the presentinvention.

FIG. 49 is a perspective view of a part of a surgical instrument, shownin FIG. 47, partially sectioned apart according to an embodiment of thepresent invention.

FIG. 50 is a perspective view of a part of a surgical instrument, shownin FIG. 47, partially sectioned apart according to an embodiment of thepresent invention.

FIG. 51 is a perspective view of a part of a surgical instrument, shownin FIG. 47, partially sectioned apart according to an embodiment of thepresent invention.

FIG. 52 is a perspective view of a surgical instrument according toanother embodiment of the present invention.

FIG. 53 is a perspective view of a surgical instrument, shown in FIG.52, partially sectioned apart according to an embodiment of the presentinvention.

FIG. 54 is a perspective view of a compression gauge jaw member brokenaway and partially sectioned apart according to an embodiment of thepresent invention.

FIG. 55 is an exploded view of a spacer assembly according to anembodiment of the present invention.

FIG. 56 is an exploded view of a spacer assembly according to anotherembodiment of the present invention.

FIG. 57 is a perspective view of a spacer base control link according toan embodiment of the present invention.

FIG. 58 is a perspective view of a spacer base control link according toanother embodiment of the present invention.

FIG. 59 is a perspective view of a spacer base control mechanismaccording to an embodiment of the present invention.

FIG. 60 is a perspective view of a spacer base control mechanismaccording to another embodiment of the present invention.

FIG. 61 is a perspective view of a spacer base control mechanismaccording to another embodiment of the present invention.

FIG. 62 is a perspective view of a spacer base control mechanismaccording to another embodiment of the present invention.

FIG. 63 is a perspective view of a spacer base control mechanismaccording to another embodiment of the present invention.

FIG. 64 is a perspective view of a spacer base control mechanismaccording to another embodiment of the present invention.

FIG. 65 is a perspective view of a power driven surgical instrumentaccording to an embodiment of the present invention.

DETAILED DESCRIPTION OF THE INVENTION

The novel features of the present invention will become apparent tothose of skill in the art upon examination of the following detaileddescription of the invention. It should be understood, however, that thedetailed description of the invention and the specific examplespresented, while indicating certain embodiments of the presentinvention, are provided for illustration purposes only because variouschanges and modifications within the spirit and scope of the inventionwill become apparent to those of skill in the art from the detaileddescription of the invention and claims that follow.

Embodiments of the presently disclosed surgical device will now bedescribed in detail with reference to the drawing figures wherein likereference numerals identify similar or identical elements. In thedrawings and in the description which follows, the term “proximal”, asis traditional, will refer to the end of the surgical device which isclosest to a physician while the term “distal” will refer to the end ofthe device which is furthest from a physician. However, surgicalinstruments are used in many orientations and positions, and these termsare not intended to be limiting and absolute. The terms “force”, “load”,and “force load” may be used interchangeably herein to describe variousmechanical forces including a reaction thereto. It should be appreciatedthat spatial terms such as vertical, horizontal, right, left or above,etc., are given herein with reference to the figures. In actualpractice, however, a surgical device or instrument may be oriented atvarious angles and, as such, these spatial terms are used relative tothe surgical device or instrument.

The present invention relates to a surgical device and method for use ina surgical procedure. More particularly, the present invention relatesto a surgical device for enabling compression of a tissue consistentlyto a predetermined thickness with a high degree of repeatability andmeasurement of a reactionary load from the compressed tissue to assistin the selection of a staple cartridge from the standard set of staplecartridges optimal for the tissue of a surgical stapling operation andto assess a condition of a tissue of a surgical operation in a surgicalprocedure. In an embodiment a surgical device of the present inventionmay be advantageously adapted for use, as an add-on accessory, mountedin a cartridge bay comprising a cartridge jaw member of an end effectorof an endoscopic surgical stapler instrument. A surgical device of thepresent invention may be configured to include retention featuressimilar to a staple cartridge for releasably mounting in an opencartridge bay, if available in a surgical stapler instrument, orotherwise fixedly integrated with a cartridge jaw member of a disposablereload unit found in certain surgical stapler instruments in the market.Advantages of a surgical device of the present invention implemented asan add-on accessory to existing surgical stapler instrument include areduced cost of use and ease of use to a physician who is alreadyfamiliar with the operation of such surgical stapler instrument. In analternate embodiment a surgical device of the present invention may beintegrated with or configured as an add-on accessory to a surgicalinstrument dedicated to implementation of the capabilities offered by asurgical device of the present invention, which may generally comprisetwo opposing jaw members comprising a tool assembly, corresponding to anend effector of a surgical stapler instrument, fixedly and operablyattached to a handle assembly via an elongate body and configured toopen and close when operated by the handle assembly. Although theimplementation and operation of a surgical device in various embodimentsof the present invention will be described in the following as itrelates to a endoscopic surgical stapler instrument and endoscopicsurgical instrument, it should be apparent to those of skill in the artthat the aspects of the present disclosure may be readily adapted foruse with other surgical stapler instruments as well as other types ofsurgical instruments.

The present invention is being discussed in terms of endoscopicprocedures and apparatus. However, use herein of terms such as“endoscopic”, should not be construed to limit the present invention toa surgical instrument for use only in conjunction with an endoscopictube (i.e., trocar). On the contrary, it is to be understood that thepresent invention may find use in any procedure where access is limitedto a small incision, including but not limited to laparoscopicprocedures, as well as open procedures.

The characteristic behavior of a tissue undergoing deformation underexternal stress load, for example, a compressive stress load applied bya pair of jaw members comprising an end effector of a surgical staplerinstrument, has been widely studied (for example, Jacob Rosen et. al.,“Biomechanical Properties of Abdominal Organs In Vivo and PostmortemUnder Compression Loads,” Journal of Biomedical Engineering, Vol. 130,pp. 1-17) and is generally represented by a stress-strain curve plot,well known to those of skill in the art, shown in FIG. 1 in an exemplaryrepresentation for a stomach tissue. In response to a compressive stressload, depicted in the vertical axis of the plot, the stomach tissueundergoes a rapid deformation, represented as strain, defined as apercentile reduction in tissue thickness, and depicted in the horizontalaxis of the plot, in response to a relatively small change in thecompressive stress load at the lower level thereof. At the higher levelthe stress-strain curve becomes close to a line indicating a linearelastic behavior of the stomach tissue characterized by an elasticmodulus defined as the largely constant slope of the stress-straincurve. This general characteristic behavior of a stomach tissue as wellas other bodily tissue under a compressive stress load is oftendescribed as a viscoelastic behavior, by those of skill in the art,exhibiting typical characteristics of both a viscous liquid and anelastic solid subject to an external compressive stress load. Theinitial rapid deformation of the stomach tissue at the lower level ofcompressive stress load is largely due to initial displacement ofviscous, liquid-like components of the tissue causing a rapid reductionin thickness of the tissue under a relatively weak compressive stressload applied to an area thereof. The elastic response of the tissue atthe higher level of compressive stress load is largely due to relativelyimmobile fibrous, solid-like components of the tissue responding to thecompressive stress load collectively with substantially elasticbehavior. At further higher up in the compressive stress load level thestrain of the tissue reaches what is known to those of skill in the artas the ultimate tensile strength or the breaking point, labeled with aletter C in FIG. 1 where the internal structure of the tissue starts tobreak down and eventually completely loses ability to recoverablyrespond to an additional compressive stress load.

The almost linear correlation between the stress and strain of a stomachtissue and, to an extent, similar behavior exhibited in other bodilytissues at the compressive stress load interval of interest,particularly, as it relates to a surgical stapling operation, indicatedby a bracket labeled with a letter S in FIG. 1, makes it possible toinfer the change in the compressive stress load acting on the stomachtissue if the change in the thickness of the stomach tissue resultingtherefrom is known and vice versa. Based on this observation, one coulddevise a practical scheme for the selection of a staple cartridge,containing staples of optimal height for a tissue of a surgical staplingoperation, from the standard set of staple cartridges, which generallyinclude steps of compressing a tissue to a predetermined thickness,i.e., to a predetermined strain; measuring a compressive stress load,i.e., a reactionary load from the compressed tissue, required to causesuch reduction in thickness; comparing the measured compressive stressload to the known optimal value for a surgical stapling operation, forexample, 8 g/mm² as previously described in the BACKGROUND, noting thesize of difference between the measured compressive stress load and theoptimal value; and based on the result of comparison, deciding whetherto select a staple cartridge with staples of formed height closest tothe compressed tissue thickness or of different formed heights takinginto account the size of difference, i.e., change the strain induced onthe tissue to a direction and level to modify the compressive stressload exerted on the tissue to be closer to the optimal value. As will bedescribed in detail hereinafter, implementation of such a scheme on aplatform of existing surgical instrument, particularly, a surgicalstapler instrument may heavily rely on being able to methodicallyconstrain the closure of the two jaw members comprising an end effectoror a tool assembly to compress a tissue consistently to a predeterminedthickness with a high degree of repeatability and to measure areactionary load from the compressed tissue.

Referring to FIGS. 2A and 2B, an exemplary surgical stapler instrument10 and an enlarged view of an end effector 20 thereof are shown.Surgical stapling instrument 10 includes a handle assembly 11, endeffector 20 and an elongate tube 12 that operatively connects handleassembly 11 and end effector 20 through a drive mechanism (not shown inthe FIGURES). End effector 20 comprises a first jaw member 21 and asecond jaw member 22. Second jaw member 22 comprises an elongate channel23, sometimes referred to as a cartridge bay, configured to receive astaple cartridge 25 having a tissue contacting surface 26. First jawmember 21 comprises an anvil having a tissue contacting surface 24 thatis aligned and pivotally engaged through a pivot mechanism (not shown)with second jaw member 22 forming a pair of opposed jaw members thatopen and close, when driven by the drive mechanism operated with handleassembly 11 by a physician, to capture and compress a tissuethere-between for stapling. Various different drive mechanisms, wellknown to those of skill in the art, are employed to actuate a pivotmechanism joining two jaw members 21, 22 to cause opening and closingthereof including a drive pin and cam groove mechanism, reciprocatingclosure tube assemblies, gear mechanisms, rack and pinion mechanism, andpulley mechanism, etc. Typically, handle assembly 11 driving endeffector 20 is configured in such a way that first and second jawmembers 21, 22 are capable of rigidly holding their approximatedpositional relationship, i.e., a locked position, when closed to captureand compress the tissue prior to the deployment and formation ofstaples. Those of skill in the art would appreciate that the exemplarysurgical stapler instrument depicted in the FIGURES comprises onesurgical stapler instrument version with which various embodiments of asurgical device of the present invention may be advantageously employed.

The pivotal engagement between two jaw members 21, 22 comprising an endeffector 20 may take various configurations including a hinge aboutwhich two jaw members 21, 22 are configured to rotate and a cam groovealong which a drive pin is configured to translate to open or close endeffector 20. The clearances built in the mechanical designs of the pivotmechanism and the drive mechanism to ensure smooth operations thereofand, to a lesser extent, unavoidable manufacturing tolerances in theparts thereof inevitably introduce a measurable play in the pivotalmotion of two jaw members 21, 22, which manifests as an inherentuncertainty in the positional relationship between two jaw members 21,22, particularly, in the relative angular position thereof even underunloaded condition, that is, without a tissue captured and compressedthere-between. Of particular significance to a device and method in anembodiment of the present invention is a variation in the relativeangular position of the two jaw members that may be appropriatelyreferred as a backlash, i.e., a tendency for the closed jaw members toopen back up, the size of which is strongly dependent on the level ofcompression of a tissue there-between. The variation in the backlashintroduces, in effect, variability in the gap distance, defined as adistance between tissue contacting surfaces 24, 26, of two jaw members21, 22 at a given position along the length of end effector 20, whichalso varies with the size of a reactionary load from the compressedtissue. The uncertainty in the gap distance due to the play in the pivotmechanism tends to become more pronounced going farther away distallyfrom pivot mechanism due to a lever arm effect. A reactionary load fromthe compressed tissue acting on two jaw members 21, 22 may add tovariability in the gap distance by potentially causing a deformation ora deflection of two jaw members 21, 22, more likely, an anvil the lessstiffer of the two, the degree of which differs depending the size ofthe reactionary load and, therefore, is not easy to estimate or measure.In practice, the gap distance has been observed to vary verysignificantly from one tissue to another mostly due to the deflection ofthe anvil, irrespective of particular brands of surgical staplerinstrument in the market, and in fact, there are no dedicated mechanismsimplemented on the existing surgical stapler instrument products toprecisely and actively control the gap distance during compression of atissue. Instead, when critically needed, for example, in case of a verythick tissue, an external constraining means is employed to control thegap distance to some extent in certain surgical stapler instruments inthe market. For this reason, a surgical stapler instrument presentlybeing marketed does not make a suitable platform on which to implementthe staple cartridge selection scheme, described previously, whichhinges on an ability to compress a tissue consistently to a well definedthickness and measure a reactionary load therefrom. A surgical deviceand method proposed in this disclosure seeks to remedy such deficienciesin a surgical stapler instrument or a new surgical instrument dedicatedfor implementation of such a scheme with a mechanical and operationalconfiguration similar to those of a surgical stapler instrument withoutrequiring a radical redesign of the instruments by providing relativelysimple features that are added-on to help bring under control thevariability in the gap distance between the two jaw members comprisingan end effector or a tool assembly and to introduce a capability to theinstruments to measure a reactionary load from the compressed tissue aswill be described hereinafter.

Referring to FIG. 3A, a compression gauge cartridge 30 is shown, in aperspective view, mounted in cartridge bay 23 of cartridge jaw member 22of end effector 20 of surgical stapler instrument 10, as shown in FIGS.2A and 2B, for compressing a tissue consistently to a predeterminedthickness and measuring a reactionary load therefrom in an embodiment ofthe present invention. Anvil jaw member 21 is omitted for clarity inFIG. 3A and a pivot mechanism joining the two jaw members 21, 22 isschematically represented by a symbol labeled with a letter P and apivotal motion by a double headed, curved arrow labeled with a letter A.In FIG. 3B compression gauge cartridge 30 is shown released fromcartridge bay 23. Referring to FIG. 3C, details of construction ofcompression gauge cartridge 30 is shown in an exploded view in anembodiment of the present invention. In a preferred embodiment of thepresent invention, compression gauge cartridge 30 for use mounted incartridge bay 23 of cartridge jaw member 22 comprising end effector 20of surgical stapler instrument 10, together with anvil jaw member 21having a tissue contacting surface 24, to compress a tissue consistentlyto a predetermined thickness and measure a reactionary load therefromfor assisting in selection of a staple cartridge optimal for a tissue ofa surgical stapling operation and assessing a condition of a tissue of asurgical operation comprises: a cartridge body 31 having a proximal end32 and a distal end 33, and a tissue supporting surface 34 correspondingto tissue contacting surface 26 of staple cartridge 25, whereincartridge body 31 may be configured for compression gauge cartridge 30to be releasably mounted in cartridge bay 23 and for tissue supportingsurface 34 to be at least at a predetermined distance from tissuecontacting surface 24 of anvil jaw member 21 when cartridge jaw member22 and anvil jaw member 21 are in a fully closed position; a force gaugeassembly 40 comprising a force transducer 41 and a compression head 45having a tissue compression face 46, wherein force gauge assembly 40 maybe supported by cartridge body 31 positioned between proximal end 32 anddistal end 33 thereof, and wherein compression head 45 comprising saidforce gauge assembly 40 may be configured and disposed so that tissuecompression face 46 thereof may lie substantially closer to tissuecontacting surface 24 of anvil jaw member 21 than tissue supportingsurface 34 of cartridge body 31; and a spacer member 50 extending fromtissue supporting surface 34 of said cartridge body 31, wherein forcegauge assembly 40 may be positioned distally with respect to spacermember 50. In an alternate embodiment tissue supporting surface 34 ofcartridge body 31 may be contoured in such a way to further reducecompression of a tissue disposed between tissue supporting surface 34and tissue contacting surface 21 when cartridge jaw member 22 and anviljaw member 21 are in a fully closed position. Further details ofcompression gauge cartridge 30 can be seen in FIG. 3D showing, in aperspective view, cartridge body 31 sectioned along the line 3D-3D shownin FIG. 3C and spaced apart in an embodiment of the present invention.As will become more clear with the following description, compressiongauge cartridge 30 is configured to allow an existing surgical staplerinstrument to be used without modification in applying a compression toa predetermined area of a tissue captured between the two jaw memberscomprising an end effector thereof consistently and with a high degreeof repeatability to a predetermined thickness substantially free ofvariations of mechanical and structural origins and measuring areactionary load from the compressed area of the tissue dynamicallythroughout the compression operation. In an embodiment of the presentinvention cartridge body 31 comprising compression gauge cartridge 30may be configured for compression gauge cartridge 30 to be releasablymounted and securely retained in cartridge bay 23 comprising cartridgejaw member 22 of end effector 20. In an alternate embodiment cartridgebody 31 comprising compression gauge cartridge 30 may be configured tobe fixedly mounted in cartridge bay 23 to be integrated with cartridgejaw member 22 of end effector 20 of surgical stapler instrument 10. Inanother alternate embodiment cartridge body 31 comprising compressiongauge cartridge 30 may be configured to be fixedly mounted in acartridge bay to be integrated with a cartridge jaw member of an endeffector comprising a disposable reload unit of a certain surgicalstapler instrument product in the market.

Referring to FIGS. 3A-3D force transducer 41 comprising force gaugeassembly 40 is depicted as having a configuration of a beam supported bycartridge body 31 housed in a cavity 35 therein in an embodiment of thepresent invention. In an alternate embodiment force transducer 41comprising force gauge assembly 40 may have a configuration of a buttonsupported by cartridge body 31 housed in a cavity 35 therein as shown inFIGS. 4A and 4B in similar arrangements to FIGS. 3A and 3D,respectively. In another alternate embodiment force transducer 41comprising force gauge assembly 40 may have a substantially planarconfiguration supported by cartridge body 31 disposed on tissuesupporting surface 34 thereof as shown in FIGS. 5A and 5B in similararrangements to FIGS. 3A and 3D, respectively. In various embodiments ofthe present invention cartridge body 31 comprising compression gaugecartridge 30 provides a structurally stable platform upon which forcetransducer 41 relies in performing a force measurement operation exertedthereon. More detailed descriptions will follow hereinafter in a sectiondedicated to the force transducer.

In an embodiment of the present invention cartridge body 31 comprisingcompression gauge cartridge 30 may be configured to include selecteddesign features similar to those found in a conventional staplecartridge that allow a conventional staple cartridge to be releasablymounted and securely retained in a cartridge bay of a cartridge jawmember during a stapling operation. In an alternate embodiment cartridgebody 31 may include additional design features for releasable mountingand secure retention thereof in a cartridge bay and safety features forsafe and effective use of a surgical stapler instrument instrumentedwith compression gauge cartridge 30 by a physician with average level ofexperience and skill in use of an ordinary surgical stapler instrument.In an embodiment, materials and method of manufacture substantiallysimilar to those used to construct a conventional staple cartridge maybe employed and appropriately adapted to manufacture cartridge body 31comprising compression gauge cartridge 30. In an alternate embodimentcartridge body 31 may include structural reinforcements and/orunconventional construction materials, not ordinarily found in aconventional staple cartridge, to ensure proper operation of force gaugeassembly 40 comprising compression gauge cartridge 30 and compression ofa tissue in cooperation with an anvil jaw member comprising an endeffector. As will be described hereinafter, the distribution of areactionary load on cartridge body 31 from a tissue under compression inoperation of surgical stapler instrument 10 instrumented withcompression gauge cartridge 30 may be different, by design, from that ona conventional staple cartridge mounted in a cartridge bay of the sameor comparable surgical stapler instrument in an embodiment of thepresent invention.

Referring to back FIGS. 3C and 3D, in an embodiment of the presentinvention cartridge body 31 may be configured to support force gaugeassembly 40 in an open cavity 35 defined therein with an opening 36disposed on tissue supporting surface 34 interconnecting cavity 35 andan external space above tissue supporting surface 34, through whichcompression head 45 comprising force gauge assembly 40 is disposed. Inan embodiment opening 36 may be hermetically capped with a seal member37 to prevent introduction of unwanted contaminant, such as bodilyfluid, into cavity 35. Seal member 37 may be configured to be in contactwith tissue compression face 46 of compression head 45 and provided withsufficient flexibility or, otherwise, a freedom of movement to allowdisplacement of compression head 45 in response to a load exertedthereto from a compressed tissue to take place substantially freely,which is generally very small and required in a normal operation offorce transducer 41, as will be described later in a dedicated section.In an alternate embodiment seal member 37 may be integrated withcompression head 45 on tissue compression face 46 thereof tosubstantially freely move concurrently therewith. In an embodimentcavity 35 may be configured, preferably, to substantially rigidly hold astationary portion of force transducer 41 of a beam configuration toprovide a structural support necessary for optimal operation thereof andto leave sufficient space to ensure unobstructed deflection of adeflectable portion of force transducer 41 and compression head engagedtherewith, which is a key aspect of force measurement operation of aforce transducer of a beam configuration, as is well known to those ofskill in the art. Referring to FIG. 4B, in an embodiment of the presentinvention cavity 35 may be configured to accommodate to rigidly holdforce transducer 41 of a button configuration and leave sufficient spacefor free movement of compression head 45 engaged therewith. In a furtherembodiment cartridge body 31 may be configured to support force gaugeassembly 40 of a planar configuration substantially on tissue supportingsurface 34 as shown in FIGS. 5A and 5B. In an embodiment a retentionfeature 49 may be provided to securely position force gauge assembly 40on tissue supporting surface 34.

Referring to FIGS. 6A and 6B, schematically showing a tissue T capturedand compressed, respectively, between anvil jaw member 21 and aconventional staple cartridge 25 representing a cartridge jaw member 22as shown in FIG. 2B, the distributed reactionary load from compressedtissue T over the length of anvil jaw member 21 comprising end effector20 often causes anvil jaw member 21 to deflect to a substantial degreetypically being less stiffer than cartridge jaw member 22 instrumentedwith staple cartridge 25. The extent, to which anvil jaw member 21deflects, strongly depends on the degree of compression of tissue T andgradually increases as one goes distally along the length of endeffector 20 from pivot mechanism P due to a cumulative nature of thereactionary load from compressed tissue T. This is a major reason why itis not practically possible to controllably compress a tissueconsistently to a known thickness with existing surgical staplerinstrument mounted with a conventional stapler cartridge in a cartridgejaw member thereof in addition the inevitable plays in the pivot anddrive mechanisms.

With a view to substantially eliminate incontrollable deflection of ananvil jaw member, comprising an end effector together with a cartridgejaw member instrumented with a compression gauge cartridge, inperforming tissue compression captured there-between, in an embodimentof the present invention, cartridge body 31, as shown in FIG. 6C in aperspective view, may be configured so that tissue supporting surface 34thereof may be at the minimum at a predetermined distance from a tissuecontacting surface of an anvil jaw member when a cartridge jaw memberand an anvil jaw member are in a fully closed position with or without atissue captured and compressed there-between. Preferably, the gapdistance, defined as a distance between tissue supporting surface 34 andthe tissue contacting surface of an anvil jaw member, at a positionalong the length of the end effector may be substantially larger thanthe largest gap distance provided by any one from the standard set ofstaple cartridges at the same position and under the same loadingcondition from the compressed tissue, if present, so that compression ofa tissue disposed over an area covered by tissue supporting surface 34may be minimized to substantially eliminate a distributed reactionaryload acting on the anvil jaw member. In an embodiment tissue supportingsurface 34 may include surface contours such as a recess 38 in order tofurther reduce compression applied to a tissue in contact therewith. Theneed to keep the tissue compression under control over the area oftissue supporting surface 34 must be balanced against the requirementfor the structural stiffness of a cartridge jaw member to guard againstdeformation thereof. Referring back to FIG. 3B, in an embodiment of thepresent invention cartridge body 31 may be configured for tissuesupporting surface 34 thereof to lie substantially even with a topportion 28 of cartridge bay 23. In an alternate embodiment, cartridgebody 31 may be configured for tissue supporting surface 34 thereof tolie substantially above top portion 28. In another alternate embodiment,cartridge body 31 may be configured for tissue supporting surface 34thereof to lie substantially below top portion 28.

Located at a predetermined position along the length of cartridge body31 on tissue supporting surface 34 thereof is an opening 36, as shown inFIGS. 3C, 3D and 4B, in an embodiment of the present invention, throughwhich compression head 45 comprising force gauge assembly 40 isdisposed. In an alternate embodiment, as shown in FIGS. 5A and 5B, forcegauge assembly 40 comprising force transducer 41 of a planarconfiguration and compression head 45 may be disposed at a predeterminedposition along the length of cartridge body 31 on tissue supportingsurface 34. In a preferred embodiment of the present inventioncompression head 45 comprising force gauge assembly 40 may be configuredand disposed with respect to cartridge body 31 so that tissuecompression face 46 thereof lie substantially above tissue supportingsurface 34 of cartridge body 31 and closer to tissue contacting surface24 of anvil jaw member 21, as shown in FIG. 2B, than tissue supportingsurface 34 of cartridge body 31 when cartridge jaw member 22 and anviljaw member 21 are in a fully closed position. Under such configuration,a tissue captured between a compression gauge cartridge mounted in acartridge bay of a cartridge jaw member and an anvil jaw memberexperiences compression substantially exclusively over the area coveredby tissue compression face 46 when two jaw members are in a fully closedposition, as schematically illustrated in FIG. 6D in an embodiment,where a predetermined gap distance over tissue compression face 46 or apredetermined thickness to which a tissue is compressed is labeled by aletter G. In an embodiment of the present invention the area coveredtissue compression face 46 may be varied in order to control areactionary load from a tissue compressed thereon and substantiallyeliminate potential deflection of an anvil jaw member resultingtherefrom. In an alternate embodiment, the position along the length ofthe end effector of compression head 45 comprising force gauge assemblymay be varied to control a lever arm effect, as previously described, ofa reactionary load from a tissue compressed thereon and substantiallyeliminate potential deflection of an anvil jaw member resultingtherefrom as schematically shown in FIG. 6E. In another alternateembodiment, the area of tissue compression face 46 and the positionalong the length of the end effector of compression head 45 may bejointly varied.

Referring to FIGS. 3C-4B and FIGS. 7A and 8A showing, in a perspectiveview, a force gauge assembly 40 comprising force transducer 41 andcompression head 45 where compression head 45 is shown spaced apart fromforce transducer 41, in an embodiment of the present invention, forcegauge assembly 40 may be disposed for compression head 45 to be locatedat a predetermined position along the length of cartridge body 31between proximal end 33 and distal end 32 thereof to provide ameasurement of a reactionary load from a tissue compressed in a gapbetween a tissue contacting surface of an anvil jaw member and tissuecompression face 46 of compression head 45. In a preferred embodimentforce transducer 41 may be a strain gauge based load cell of variousconfigurations capable of generating an electrical signal whenstimulated including load cells of a beam configuration including, forexample, a cantilever bending beam and a parallel bending beam, asschematically illustrated in FIG. 7A, and of a button configuration, asschematically illustrated in FIG. 8A, as are well known to those ofskill in the art. Strain gauge based load cells are widely availablefrom a multitude of vendors at relatively low price levels due to theirwide spread uses in industrial applications and consumer weightmeasurement equipments such as personal and kitchen electronic scales.In an embodiment of the present invention there is provided a signalconduction means 48 electrically connected to force transducer 41 forconducting a signal therefrom to a force transducer indicator or acontroller (not shown in the FIGURES) disposed remotely from thesurgical site, for example, external to a surgery patient. Appropriatesignal conduction means 48 for a strain gauge based load cell and othertypes of load cell generating an electric signal includes a flexibleflat cable and thin gauge electrical wires, both of which are widelyavailable commercially at low cost and of such a small thickness to beable to freely pass through an annular gap between an elongate tube of asurgical stapler instrument and the inside wall of a trocar throughwhich the instrument is deployed. In an alternate embodiment forcetransducer 41 may be a load cell of a planar configuration, asschematically illustrated in FIG. 9A, a piezoelectric load cell capableof generating an electrical signal when stimulated, commerciallyavailable from a multiple vendors, and a resistive film type forcesensor capable of generating an electrical signal when stimulated, forexample, FlexiForce Sensor® commercially available from Tekscan Inc.

Preferably, signal conduction means 48, appropriately selected for forcetransducer 41, may work bi-directionally conducting a signal from forcetransducer 41 to a force transducer indicator or a controller disposedremotely from a surgical site for signal processing and display ofresult therefrom and providing a power and control signals needed foroperation of force transducer. As shown in FIG. 7C, signal conductionmeans 48 may be routed to pass around a distal end of cartridge jawmember 23 as it exits cartridge body 31 in an embodiment of the presentinvention. As shown in FIG. 7D, in an alternate embodiment, signalconduction means 48 may be configured to comprise at least two parts,one part connected to force transducer 41 on one end and terminatingwith a connector 43 on the other end, and the other part connected to aforce transducer indicator on one end and terminating to a connector 42complementary to connector 43 on the other end. In an embodiment a forcetransducer indicator or a controller may be disposed externally to thepatient and may include an off-the-shelf, commercial weight indicatorunit, a custom designed, microprocessor controlled indicator and asignal processor electronics controlled by a computer with a display. Inan alternate embodiment of the present invention, at least for a forcetransducer configured to be electrically powered and generate anelectric signal when stimulated, an electrical power source, forexample, a battery, and at least a part of processing and displaycircuitry may be disposed in and supported by a cartridge bodycomprising a compression gauge cartridge. In another alternateembodiment the cartridge body may further include a wirelesscommunication means for wirelessly sending a signal to an indicator or acontroller disposed externally from a surgical site for furtherprocessing and display.

In an embodiment, force transducer 41 may be dimensionally adaptable foruse supported in a cartridge body disposed in a cartridge bay of acartridge jaw member of an end effector. In an alternate embodiment,force transducer 41 may be dimensionally adaptable for use supported inone of the jaw members comprising an end effector of a surgicalinstrument dedicated to implementation of the present invention.Preferably, the deflection of a deflectable portion of force transducer41, which normally accompanies operation of force transducer 41 invarying forms and to a different degree, at a maximum level of thereactionary load from the compressed tissue does not exceed apredetermined fraction of a strain induced on the tissue by thecompression applied thereto. As previously described in reference toFIG. 1, a relatively small change in the strain of a tissue, forexample, due to interaction with force transducer 41, could result in asubstantial variation in the stress thereof potentially skewing themeasurement of the reactionary load therefrom. Typically, a maximumdeflection a strain gauge based load cell or a hydraulic load cellexperiences at the load limit does not exceed a few thousandths of aninch easily satisfying the requirement for use on a tissue. A load cellof a planar configuration, at least those include in the examplesdescribed previously, does not require any deflection to perform a forcemeasurement.

In an embodiment of the present invention, compression head 45comprising force gauge assembly 40 mechanically interfaces between atissue undergoing compression and force transducer 41 for measuring areactionary force therefrom. Referring to FIGS. 3A-5B and 7A, 8A and 9A,in an embodiment compression head 45 may be configured and disposed,with respect to cartridge body 31, to contact force transducer 41 on oneend, a transducer contact face 47, and the tissue on the other end,tissue compression face 46 participating in compression of the tissuecooperating with anvil jaw member 21 and transferring a reactionary loadfrom the compressed tissue to force transducer 41 substantially withouta mechanical loss in a manner conducive to the mode of operation of aparticular force transducer. In an embodiment compression head 45 may beconfigured and disposed, with respect to cartridge body 31, so thattissue compression face 46 thereof lies substantially closer to tissuecontacting surface 24 of anvil jaw member 21 than tissue supportingsurface 34 of cartridge body 31 as schematically shown in FIG. 6Dshowing, in a side elevation view, a tissue compressed betweencompression gauge cartridge 30 and anvil jaw member 21 comprising an endeffector in a closed position. This is to deliberately encourage thecompression of a tissue to take place preferentially over an area, outof tissue contacting surface 24 of an anvil jaw member 21, covered bytissue compression face 46 and to minimize tissue compression overtissue supporting surface 34 to a predetermined gap distance betweentissue compression face 46 and tissue contacting surface 24 indicated bya letter G in FIG. 6D.

In various embodiments of the present invention compression head 45 maytake on different configurations and mechanical characteristics thatsuit a particular application of a compression gauge cartridge of thepresent invention. For example, as shown in FIGS. 7B, 8B and 9B,configuration of transducer contact face 47 may be varied to accommodateforce transducer 41 of different geometry, and the area and profile oftissue compression face 46 may be predetermined, for example, to controlthe degree of tissue compression optionally in conjunction withvariation of a gap distance between tissue compression face 46 andtissue contacting surface 24, which is primarily controllable with aspacer member 50, as will be described hereinafter. In an embodimentcompression head 45 may be of substantially rigid construction to beable to transfer a reactionary load imparted on tissue compression face46 thereof to transducer contact face 47 without a mechanical loss evenwhen the reactionary load is unevenly distributed over tissuecompression face 46. In an alternate embodiment compression head 45 maybe of substantially rigid construction to be able to resist deformationunder a compressive load imparted thereon by the compressed tissue butotherwise of flexible nature as may be the case for a relatively thincompression head that may be employed for a force transducer of a planarconfiguration as schematically illustrated in FIG. 9B. In an embodimentof the present invention compression head 45 may be configured to float,that is, be left unattached other than the mechanical engagement withforce transducer 41 through transducer contact face 47 thereof. In analternate embodiment compression head 45 may be fixedly joined withcartridge body 31 in such a configuration that allows a displacementthereof, and concomitant deflection of force transducer 41, in responseto a reactionary load from a compressed tissue to occur through apredetermined deformation of compression head 45. In an exemplaryembodiment, as previously described with reference to FIGS. 3C and 3D,compression head 45 may be fixedly joined with seal member 37 havingsufficient flexibility to provide freedom of movement thereto. In analternate exemplary embodiment, as shown in FIG. 8C, compression head 45may be configured and disposed to cantilever with respect to a fixedposition 49 on cartridge body 31 with tissue compression face 46 thereofpositioned remotely from fixed position 49 and transducer contact face47 positioned there-between. In another alternate exemplary embodiment,compression head 45 may comprise a deformable member 44 fixedly joinedwith cartridge body 31 in a predetermined pattern, for example, alongthe periphery as shown in FIG. 8D schematically illustrating a cartridgebody sectioned and spaced apart, and a force gauge assembly, that isconfigured to flex substantially perpendicularly, i.e., up and down,with respect to tissue contacting surface 46 of cartridge body 31.

Referring to FIGS. 3A-5B, in a preferred embodiment of the presentinvention spacer member 50 may be of a rigid construction extending fromtissue supporting surface 34 of cartridge body 31 disposed betweenproximal end 33 and distal end 32 thereof and proximal to compressionhead 45 comprising force gauge assembly 40. In an embodiment spacermember 50 may be configured to be a positive stop constraining a pivotalmotion of the two jaw members comprising an end effector andsubstantially defining the closest gap distance at the position ofspacer member 50 between tissue contacting surfaces 24, 26 of anvil jawmember 21 and cartridge jaw member 22. In the absence of a deflection ofan anvil jaw member, spacer member 50 also determines a predeterminedgap distance between tissue compression face 46 of compression head 45and tissue contacting surface 24 of anvil jaw member 21 with two jawmembers comprising an end effector in a fully closed position. Spacermember 50 also plays an important role in substantially eliminatingvariation in the gap distance stemming from a play present in the pivotand drive mechanisms of a pivotal joint of the two jaw memberscomprising an end effector. Referring to FIGS. 10A and 10B schematicallyshowing, in a side elevation view, a positional relationship between acartridge jaw member represented by compression gauge cartridge 30 andan anvil jaw member in a fully closed position, in an embodiment of thepresent invention, spacer member 50 may be dimensioned to make the twoplanes, substantially defined by tissue supporting surface 34 and tissuecontacting surface 24, respectively, to be substantially parallel witheach other in providing a predetermined gap distance G between tissuecompression face 46 and tissue contacting surface 24. In an alternateembodiment spacer member 50 may be dimensioned to make the two planes tobe at a predetermined angle with each other in providing a predeterminedgap distance G between tissue compression face 46 and tissue contactingsurface 24. In a further embodiment spacer member 50 may be dimensionedso that substantially all the plays in a pivot mechanism and a drivemechanism of a pivotal joint of the two jaw members are fully taken upwhen the two jaw members are in fully closed position as will be furtherdescribed in the following section.

In a preferred embodiment of the present invention, spacer member 50comprising compression gauge cartridge 30 may be a block of a rigidconstruction fixedly joined with cartridge body 31. As shown in FIG.11A, in an embodiment cartridge body 31 and spacer member 51 may beconfigured so that the position of spacer member 51 along the length ofcartridge body 31 may be changed to suit a particular application of acompression gauge cartridge of the present invention. Spacer member 50plays a significant role in substantially eliminating variation in thepositional relationship between the two jaw members comprising an endeffector due to plays present in the pivot and drive mechanisms of apivotal joint of the two jaw members by acting as a rigid fulcrumdisposed between the pivot mechanism and a compression head comprising aforce gauge assembly that forces the plays to be fully taken up when thetwo jaw members reach a fully closed and, in some cases, lockedposition. Even when the tissue contacting surface of the anvil jawmember comes to rest making contact with the spacer member as the twojaw members close driven by the drive mechanism, the drive mechanismcontinues to drive the pivot mechanism to rotate one or both of the jawmembers with respect to the point of contact between the anvil jawmember and the spacer member until all the plays in the pivot and drivemechanisms are fully taken up and the pivotal motion of the two jawmembers comes to a solid stop reaching a final positional relationshipthere-between. Since, in practice, the force involved in driving thepivotal motion of the two jaw members are, by design, much larger thanthe largest reactionary load normally expected from a compressed tissuebetween the two jaw members comprising an end effector of a surgicalstapler instrument, the final positional relationship between the twojaw members thus achieved remains substantially undisturbed even whenthe two jaw members are acted upon from the reactionary load from acompressed tissue there-between and is solely determined by the positionand configuration of spacer member 50. Barring potential deflection ofthe anvil jaw member under a reactionary load from a compressed tissue,which can be effectively kept under control as previously described,spacer member 50 thus enables a surgical stapler instrument implementedwith a compression gauge cartridge of the present invention to be used,without modification, to provide a predetermined gap distance, betweenthe compression face of the compression head and the tissue contactingsurface of the anvil jaw member, consistently and with high degree ofrepeatability, and concomitantly to compress a tissue consistently to athickness corresponding to the predetermined gap distance.

In an embodiment of the present invention, a spacer member alsofunctions as a tissue stop defining a proximal most position along thecartridge body to which a tissue can be introduced between the two jawmembers comprising an end effector. Referring to FIGS. 11B and 11C, inan embodiment spacer member 55, 60 may further comprise a spacerextension member 57, 62 for preventing a portion of a tissue gettingcaught, while being captured, and subsequently pinched between a spacermember and a tissue contacting surface of an anvil jaw member as the twojaw members are closed. As shown in FIG. 11B, in an embodiment spacerextension member 57 may be of a retractable/extendable type configuredto move in and out of a spacer member body 56, for example, a spring 58loaded plunger or detent biased to extend out of a cavity in spacermember body 56 to a preset limit and to follow the pivotal motion of thetwo jaw members keeping the gap between the spacer member and the tissuecontacting surface of an anvil jaw member closed. In an alternateembodiment, as shown in FIG. 11C, spacer extension member 62 may be of acollapsible/expandable type including an air filled bladder, resilientfoam, a metal spring element and a leaf spring element made of a stiffpolymer film, etc, configured to require a minimal force to be collapseddown to a spacer member body 61. Referring to FIG. 11D, in an embodimenta compression gauge cartridge may comprise a protective cover 39providing protection, for example, undesirable impact during handling,over at least part of cartridge body 31 thereof, preferably, includingthe general area around the position of the force gauge assembly.

Referring to FIGS. 12A-12C showing a spacer member, and a cartridge body31 and a cartridge bay 23 broken away and sectioned apart, in anembodiment of the present invention, a spacer member comprising acompression gauge cartridge may be configured so that the height thereofover the tissue supporting surface of the cartridge body, i.e., thevertical extent the spacer member extends from the tissue supportingsurface, may be adjusted. As shown in FIG. 12A, in an embodiment of thepresent invention, an adjustable spacer member 65 having an anvilcontacting face 66 may be mounted on a threaded base 67 of a genderdisposed in a hole 69 in cartridge body 31 with a matching thread of anopposite gender so that the vertical position of anvil contacting face66 may be adjusted by turning a control stem 68 fixedly joined withthreaded base 67 and disposed through a slot normally found in cartridgebay 23. As shown in FIG. 12B, in an alternate embodiment, an adjustablespacer member 70 having an anvil contacting face 71 may comprise a rigidbase 72 disposed in a hole 75 in cartridge body 31 and on a wedge shapeplatform 73 joined with a control stem 74 disposed through a slot incartridge bay 23 so that the vertical position of anvil contacting face71 may be adjusted and locked in a position by sliding control stem 74along the slot. As shown in FIG. 12C, in another alternate embodiment,an adjustable spacer member 76 may be configured to have a nestedstructure comprising a stationary base 77 and a movable plunger 78slidably engaged with stationary base 77 in a hole 81 for verticalmovement with respect to the tissue supporting surface and to include atleast one break member 79 with a predetermined breaking mechanism, forexample, a sharp edge, drivable with control stems 80 fixedly joinedtherewith and disposed through a slot in cartridge bay 23 so thatmovable plunger 78 may be securely held immobile once the desiredvertical position thereof is reached. In an embodiment adjustable spacermember 65, 70, 76 may be configured with a bias spring that drivesadjustable spacer member or a movable part thereof to a final positionwhen triggered by a predetermined event, an example of which will bedescribed hereinafter.

As shown in FIGS. 12D and 12E, in an embodiment of the present inventiona spacer member 100 may be configured to include an axle 104, a springelement 103 and at least one flap member 101, and to be disposed in acavity 102 in a cartridge body comprising a compression gauge cartridgewith axel 104 rotatably mated with a pair of holes 105 in the cartridgebody so that spacer member 100 may pivot with respect to the cartridgebody around axle 104. Spring element 103 may be configured to biasspacer member 100 so that it remains upright with respect to thecartridge body ready to withstand the downward load from the anvilmember when the two jaw members comprising the end effector are in afully closed position. At least one flap member 101 may be configuredand disposed with respect to spacer member 100 so that it may be flippedproximally and distally therewith when acted on by the proximal anddistal ends of a trocar, respectively, during insertion and removalthere-through of a surgical stapler instrument instrumented with thecompression gauge cartridge. In an embodiment spacer member 100 may berotated to reduce the height thereof above the cartridge body, asschematically shown in FIG. 12E, manually by a physician prior toinsertion of a surgical stapler instrument or automatically by theinteraction thereof with the distal end of the trocar during removal ofa surgical stapler instrument. A spacer member of such a configurationwould enable use of a compression gauge cartridge with a spacer memberso tall that would make an end effector of a surgical stapler instrumentinstrumented with the compression gauge cartridge impassable through anormally used trocar even with the jaw members in a fully closedposition.

Surgical stapler instrument products of a design, like any otherengineering products, inherently includes certain variations in theirmechanical performance, which, by design, are not of significance inoriginally intended uses in surgical stapling operation but maynegatively affect uses of a surgical stapler instrument instrumentedwith a compression gauge cartridge of the present invention. Forexample, such variations could manifest between different productionlots, for example, due to change in production steps and/or even betweendifferent instruments from the same production lot, for example, due tochanges in the manufacturing tolerances of parts and/or subassemblies.As described previously, changes in the plays in the pivot and drivemechanism of a surgical stapler instrument, for example, resulting fromvariations in manufacturing tolerances may degrade the precision in thefinal positional relationship between the two jaw members in a fullyclosed and locked position and, in turn, the predetermined gap distancebetween the tissue compression face of the compression head and thetissue contacting surface of the anvil jaw member corresponding to apredetermined thickness to which a tissue is compressed. To circumventthe potential impact these variations may have on the performance of acompression gauge cartridge mounted on a surgical stapler instrument orin a surgical compression gauge instrument, in various embodiments ofthe present invention, there are provided methods for calibrating thegap distance between the tissue compression face of the compression headand the tissue contacting surface of the anvil jaw member. Referring toFIG. 13A showing, in a side elevation view, an anvil jaw member 21 and acompression gauge cartridge 30 representing a cartridge jaw member, inan embodiment a gap distance calibration method comprises steps of: (1)positioning a reference block 85 over a compression head 45 of heightcorresponding to a predetermined gap distance between tissue compressionface 46 of compression head 45 and the tissue contacting surface 24 ofanvil jaw member 21; (2) fully closing the two jaw members of the endeffector; and (3) adjusting the height of an adjustable spacer member 90until the load cell indicator reads zero. In an embodiment the height ofreference block 85 may be fine tuned to reflect possible deflection ofanvil jaw member 21 due to a reactionary load from reference block 85during the gap distance calibration procedure. For example, referenceblock 85 may be made taller than a predetermined target gap distance toaccount for deflection of anvil jaw member 21. In an embodiment fullyclosing the two jaw members may involve operating a handle assemblycomprising a surgical stapler instrument or a surgical compression gaugeinstrument to close the two jaw members until the handle assemblyreaches a locked state corresponding to a limit of the closingoperation. In an alternate embodiment a gap distance calibration methodcomprises steps of: (1) positioning reference block 85 over acompression head 45 of height corresponding to a predetermined gapdistance between tissue compression face 46 of compression head 45 andtissue contacting surface 24 of anvil jaw member 21; (2) fully closingthe two jaw members of the end effector; and (3) adjusting the height ofadjustable spacer member 90 until it touches tissue contacting surface24 of anvil jaw member 21. In another alternate embodiment a gapdistance calibration method comprises steps of: (1) positioning areference material over a compression head 45 of known tensile propertyand dimension between tissue compression face 46 of compression head 45and tissue contacting surface 24 of anvil jaw member 21; (2) fullyclosing the two jaw members of the end effector; and (3) adjusting theheight of adjustable spacer member 90 until the load cell indicatorreads a predetermined value indicating the reference material iscompressed to a thickness corresponding to a predetermined gap distancebetween tissue compression face 46 of compression head 45 and tissuecontacting surface 24 of anvil jaw member 21. As shown in FIGS. 13B and13C, in an embodiment of the present invention a protective cover 87 maybe configured to comprise a built-in reference block 88 and a triggermember 91 for causing a spring 92 to drive a locking mechanism 73, 74for adjustable spacer member 71 to facilitate the gap calibrationprocedure.

Referring to FIG. 14, in an embodiment of the present invention, acompression gauge cartridge 30 may comprise two parts 96, 97,preferably, one part 96 including a force gauge assembly 40 and theother part 97 including a spacer member 95, that are configured to bereleasably joined with each other. In an embodiment part 96 may be apart of compression gauge cartridge 30 that can be effectivelyre-sterilized and part 97 difficult to re-sterilize, for example, due tointernal structures present if spacer member 95 is an adjustable spacermember as previously described. After use, part 96 may be kept for reusefollowing a re-sterilization and used part 97 may be discarded andexchanged with a new one.

Referring to FIG. 15, in an embodiment of the present invention, asurgical compression gauge instrument 110 for compressing a tissueconsistently to a predetermined thickness and measure a reactionary loadtherefrom for assisting selection of a staple cartridge and assessingthe condition of the tissue comprises: a handle portion 111; a bodyportion 112 extending distally from handle portion 111 and defining alongitudinal axis; and a tool assembly 120 at the distal end of andoperatively connected to body portion 112, tool assembly 120 comprisingan anvil jaw member 121 having a tissue contacting surface 122 and acompression gauge jaw member 125, configured to open and close whenoperated by handle portion 111, wherein compression gauge jaw member 125having a proximal end 126 and a distal end 127, and a tissue supportingsurface 128 comprises a force gauge assembly 129 comprising a forcetransducer (not shown in the FIGURE) and a compression head 130 having atissue compression face 131, supported by compression gauge jaw member125 positioned between proximal end 126 and distal end 127 thereof, andwherein compression head 130 of force gauge assembly 129 is disposed sothat tissue compression face 131 thereof lies substantially closer totissue contacting surface 122 of anvil jaw member 121 than tissuesupporting surface 128 of compression gauge jaw member 125; and a spacermember 132 extending from tissue supporting surface 128 comprisingcompression gauge jaw member 125, wherein force gauge assembly 129 ispositioned distally with respect to spacer member 132.

In a preferred embodiment of the present invention, a method forselecting a staple cartridge from the standard set of staple cartridges,each containing staples of a predetermined height, optimal for a tissueof a surgical stapling operation comprises steps of: mounting acompression gauge cartridge of the present invention in a cartridge bayof a cartridge jaw member comprising an end effector, together with ananvil jaw member, of a surgical stapler instrument, a spacer member ofwhich is configured to consistently provide a gap distance,corresponding to a height of staples contained in a predeterminedcartridge from the set of standard staple cartridges, between a tissuecompression face of a compression head comprising a force gauge assemblycomprising said compression gauge cartridge and a tissue contactingsurface of said anvil jaw member; capturing a tissue between saidcartridge jaw member and said anvil jaw member; closing said cartridgejaw member and said anvil jaw member to compress said tissue capturedbetween said tissue compression face and said tissue contacting surfaceto a predetermined thickness corresponding to said gap distancethere-between; reading out a reactionary load from said compressedtissue displayed on a force transducer indicator; comparing saidreactionary load reading with a value known to be optimal for a staplingoperation of said tissue to determine if said reactionary load is case(1) within, case (2) below or case (3) above a window of a predeterminedwidth around said optimal value and how large a size of difference is incases (2) and (3); selecting a staple cartridge from the standard set ofstaple cartridges containing staples of a height corresponding to saidpredetermined thickness of said compressed tissue if the result ofcomparison is case (1), or a staple cartridge containing staples of aheight smaller than said predetermined thickness of said compressedtissue taking into account said size of difference if the result ofcomparison is case (2), or a staple cartridge containing staples of aheight larger than said predetermined thickness of said compressedtissue taking into account said size of difference if the result ofcomparison is case (3). In an alternate embodiment, a method forselecting a staple cartridge from the standard set of staple cartridges,each containing staples of a predetermined height, optimal for a tissueof a surgical stapling operation may further comprise a step of waitingfor a predetermined length of time after closing said cartridge jawmember and said anvil jaw member to compress said tissue.

In an alternate embodiment of the present invention, a method forselecting a staple cartridge from the standard set of staple cartridges,each containing staples of a predetermined average height, optimal for atissue of a surgical stapling operation comprises steps of: mounting acompression gauge cartridge of the present invention in a cartridge bayof a cartridge jaw member comprising an end effector, together with ananvil jaw member, of a surgical stapler instrument, a spacer member ofwhich is configured to consistently provide a gap distance,corresponding to an average height of staples contained in apredetermined cartridge from the set of standard staple cartridges,between a tissue compression face of a compression head comprising aforce gauge assembly comprising said compression gauge cartridge and atissue contacting surface of said anvil jaw member; capturing a tissuebetween said cartridge jaw member and said anvil jaw member; capturing atissue between said cartridge jaw member and said anvil jaw member;closing said cartridge jaw member and said anvil jaw member to compresssaid tissue captured between said tissue compression face and saidtissue contacting surface to a predetermined thickness corresponding tosaid gap distance there-between; reading out a reactionary load fromsaid compressed tissue displayed on a force transducer indicator;comparing said reactionary load reading with a value known to be optimalfor a stapling operation of said tissue to determine if said reactionaryload is case (1) within, case (2) below or case (3) above a window of apredetermined width around said optimal value and how large a size ofdifference is in cases (2) and (3); selecting a staple cartridge fromsaid standard set of staple cartridges containing staples of an averageheight corresponding to said predetermined thickness of said compressedtissue if the result of comparison is case (1), or a staple cartridgecontaining staples of an average height smaller than said predeterminedthickness of said compressed tissue taking into account said size ofdifference if the result of comparison is case (2), or a staplecartridge containing staples of an average height larger than saidpredetermined thickness of said compressed tissue taking into accountsaid size of difference if the result of comparison is case (3). In analternate embodiment, a method for selecting a staple cartridge from thestandard set of staple cartridges, each containing staples of apredetermined average height, optimal for a tissue of a surgicalstapling operation may further comprise a step of waiting for apredetermined length of time after closing said cartridge jaw member andsaid anvil jaw member to compress said tissue.

In another alternate embodiment of the present invention, a method forselecting a staple cartridge from the standard set of staple cartridges,each containing staples of a predetermined height, optimal for a tissueof a surgical stapling operation comprises steps of: mounting acompression gauge cartridge of the present invention in a cartridge bayof a cartridge jaw member comprising an end effector, together with ananvil jaw member, of a surgical stapler instrument, a spacer member ofwhich is configured to consistently provide a gap distance,corresponding to a height of staples contained in a green cartridge fromthe set of standard staple cartridges, between a tissue compression faceof a compression head comprising a force gauge assembly comprising saidcompression gauge cartridge and a tissue contacting surface of saidanvil jaw member; capturing a tissue between said cartridge jaw memberand said anvil jaw member; closing said cartridge jaw member and saidanvil jaw member to compress said tissue captured between said tissuecompression face and said tissue contacting surface to a predeterminedthickness corresponding to said gap distance there-between; reading outa reactionary load from said compressed tissue displayed on a forcetransducer indicator; comparing said reactionary load reading with avalue known to be optimal for a stapling operation of said tissue todetermine if said reactionary load is case (1) within, case (2) below orcase (3) above a window of a predetermined width around said optimalvalue; selecting a green cartridge from the standard set of staplecartridges if the result of comparison is case (1) or a blue cartridgeif the result of comparison is case (2), or a black cartridge if theresult of comparison is case (3). In an alternate embodiment, a methodfor selecting a staple cartridge from the standard set of staplecartridges, each containing staples of a predetermined height, optimalfor a tissue of a surgical stapling operation may further comprise astep of waiting for a predetermined length of time after closing saidcartridge jaw member and said anvil jaw member to compress said tissue.

In an alternate embodiment of the present invention, a method forselecting a staple cartridge from the standard set of staple cartridges,each containing staples of a predetermined height, optimal for a tissueof a surgical stapling operation comprises steps of: mounting acompression gauge cartridge of the present invention in a cartridge bayof a cartridge jaw member comprising an end effector, together with ananvil jaw member, of a surgical stapler instrument, a spacer member ofwhich is configured to consistently provide a gap distance between atissue compression face of a compression head comprising a force gaugeassembly comprising said compression gauge cartridge and a tissuecontacting surface of said anvil jaw member; capturing a tissue betweensaid cartridge jaw member and said anvil jaw member; closing saidcartridge jaw member and said anvil jaw member to compress said tissuecaptured between said tissue compression face and said tissue contactingsurface to a predetermined thickness corresponding to said gap distancethere-between; reading out a reactionary load from said compressedtissue displayed on a force transducer indicator; providing a referencetissue for which an optimal staple height for a surgical staplingoperation is known; comparing said reactionary load reading with areactionary load from said reference tissue compressed to saidpredetermined thickness over the same area of said reference tissue asthat of said tissue compression face of said compression head todetermine if said reactionary load is case (1) within, case (2) below orcase (3) above a window of a predetermined width around said reactionaryload from said reference tissue and how large a size of difference is incases (2) and (3); selecting a staple cartridge from the standard set ofstaple cartridges containing staples of a height known to be optimal forsaid reference tissue if the result of comparison is case (1), or astaple cartridge containing staples of a height smaller than that ofstaples known to be optimal for said reference tissue taking intoaccount said size of difference if the result of comparison is case (2),or a staple cartridge containing staples of a height larger than that ofstaples known to be optimal for said reference tissue taking intoaccount said size of difference if the result of comparison is case (3).In an alternate embodiment, a method for selecting a staple cartridgefrom the standard set of staple cartridges, each containing staples of apredetermined height, optimal for a tissue of a surgical staplingoperation may further comprise a step of waiting for a predeterminedlength of time after closing said cartridge jaw member and said anviljaw member to compress said tissue.

Referring to FIG. 16, showing a compression gauge cartridge 30 in aperspective view in an embodiment of the present invention, compressiongauge cartridge 30 for use mounted in a cartridge bay of a cartridge jawmember comprising an end effector of a surgical stapler instrument,together with an anvil jaw member having a tissue contacting surface, tocompress a tissue so that said cartridge jaw member and said anvil jawmember come to a predetermined angular positional relationship with eachother, as indicated in FIG. 17 by a label AG in a schematicrepresentation of an anvil jaw member 21 and compression gauge cartridge30, and measure a reactionary load therefrom for assisting in selectionof a staple cartridge optimal for a tissue of a surgical staplingoperation comprises: a cartridge body 31 having a proximal end 32 and adistal end 33, and a tissue supporting surface 34, wherein cartridgebody 31 may be configured for compression gauge cartridge 30 to bereleasably mounted in said cartridge bay and for tissue supportingsurface 34 to be at least at a predetermined distance from said tissuecontacting surface of said anvil jaw member when cartridge jaw memberand said anvil jaw member are in a fully closed position; and a forcegauge assembly 40 comprising a force transducer and a compression headhaving a tissue compression face, wherein force gauge assembly 40 may besupported by cartridge body 31 positioned between proximal end 32 anddistal end 33 thereof, and wherein said compression head comprising saidforce gauge assembly 40 may be configured and disposed so that saidtissue compression face thereof may lie substantially closer to saidtissue contacting surface of said anvil jaw member than tissuesupporting surface 34 of cartridge body 31. In an alternate embodimenttissue supporting surface 34 of cartridge body 31 may be contoured insuch a way to further reduce compression of a tissue disposed betweentissue supporting surface 34 and said tissue contacting surface whensaid cartridge jaw member and said anvil jaw member are in a fullyclosed position. Compression gauge cartridge 30 is configured to allowan existing surgical stapler instrument to be used without modificationin applying a compression to a predetermined area of a tissue capturedbetween the two jaw members comprising an end effector thereof so thatthe two jaw members come to a predetermined positional relationship witheach other and measuring a reactionary load from the compressed area ofthe tissue. In an embodiment of the present invention cartridge body 31comprising compression gauge cartridge 30 may be configured forcompression gauge cartridge 30 to be releasably mounted and securelyretained in a cartridge bay comprising a cartridge jaw member of an endeffector. In an alternate embodiment cartridge body 31 comprisingcompression gauge cartridge 30 may be configured to be fixedly mountedin a cartridge bay to be integrated with a cartridge jaw member of anend effector of a surgical stapler instrument. In another alternateembodiment cartridge body 31 comprising compression gauge cartridge 30may be configured to be fixedly mounted in a cartridge bay to beintegrated with a cartridge jaw member of an end effector comprising adisposable reload unit of a certain surgical stapler instrument productin the market. In an alternate embodiment of the present invention thedimension of a cartridge body comprising a compression gauge cartridgemay be varied to suit particular application thereof. For example, asshown in FIG. 19, cartridge body 31 may be configured to be shorter thana conventional staple cartridge along the length of a cartridge bay.

Referring to FIG. 18, in an embodiment of the present invention, asurgical stapler instrument 10 may further include a spacer block 13 ofa predetermined height disposed at a handle 11 comprising surgicalstapler instrument 10 for defining a predetermined extent handle 11 maybe operated to close a cartridge jaw member and an anvil jaw membercomprising an end effector 20 comprising surgical stapler instrument 10so that said cartridge jaw member and said anvil jaw member come to apredetermined angular positional relationship with each other.

In an alternate embodiment of the present invention, a method forselecting a staple cartridge from the standard set of staple cartridges,each containing staples of a predetermined height, optimal for a tissueof a surgical stapling operation comprises steps of: mounting acompression gauge cartridge of the present invention in a cartridge bayof a cartridge jaw member comprising an end effector, together with ananvil jaw member having a tissue contacting surface, of a surgicalstapler instrument; capturing a tissue between said cartridge jaw memberand said anvil jaw member; closing said cartridge jaw member and saidanvil jaw member to compress said tissue captured there-between so thatsaid cartridge jaw member and said anvil jaw member come to apredetermined angular positional relationship with each other; readingout a reactionary load from said compressed tissue displayed on a forcetransducer indicator; providing a reference tissue for which an optimalstaple height for a surgical stapling operation is known; comparing saidreactionary load reading with a reactionary load from said referencetissue compressed so that said cartridge jaw member and said anvil jawmember come to said predetermined angular positional relationship witheach other to determine if said reactionary load is case (1) within,case (2) below or case (3) above a window of a predetermined widtharound said reactionary load from said reference tissue and how large asize of difference is in cases (2) and (3); selecting a staple cartridgefrom the standard set of staple cartridges containing staples of aheight known to be optimal for said reference tissue if the result ofcomparison is case (1), or a staple cartridge containing staples of aheight smaller than that of staples known to be optimal for saidreference tissue taking into account said size of difference if theresult of comparison is case (2), or a staple cartridge containingstaples of a height larger than that of staples known to be optimal forsaid reference tissue taking into account said size of difference if theresult of comparison is case (3). In an alternate embodiment, a methodfor selecting a staple cartridge from the standard set of staplecartridges, each containing staples of a predetermined height, optimalfor a tissue of a surgical stapling operation may further comprise astep of waiting for a predetermined length of time after closing saidcartridge jaw member and said anvil jaw member to compress said tissue.

Referring to FIG. 20, showing a compression gauge cartridge 30 in aperspective view in an embodiment of the present invention, compressiongauge cartridge 30 for use mounted in a cartridge bay of a cartridge jawmember comprising an end effector of a surgical stapler instrument tocompress a tissue and measure a reactionary load therefrom for assistingin selection of a staple cartridge optimal for a tissue of a surgicalstapling operation comprises: a cartridge body 31; and a force gaugeassembly 40, an electronic circuit module 135 including a signalprocessing circuit for conditioning and digitizing a signal from saidforce gauge assembly 40 and wireless transmission circuit, and a batterymodule 136 for providing operational power to said force gauge assembly40 and said electronic circuit module 135 housed in said cartridge body31. In an embodiment, there is provided a corresponding force transducerindicator (not shown in the FIGURE) configured to receive and display awireless signal from compression gauge cartridge 30 indicating theresult of measurement by said force gauge assembly 40. In an embodimentsaid battery module 136 may be of rechargeable type.

In an embodiment of the present invention there is provided acompression gauge cartridge comprising a cartridge body configured toallow a spacer member to be extended to and held in position at apredetermined extent or height above the tissue supporting surface ofthe cartridge body and retracted to or below the height required forinsertion and withdrawal through a trocar of the surgical staplerinstrument the end effector of which the compression gauge cartridge ismounted in. Such a compression gauge cartridge enables a surgicalstapler instrument implemented therewith to probe a tissue, that is,compress a tissue and measure a reactionary load therefrom, atcompressed tissue thickness that cannot be accommodated by a compressiongauge cartridge with a fixed height spacer member due to constraint onthe height thereof imposed by the size of a trocar through which thesurgical stapler instrument must be inserted and withdrawn. Similarly, acompression gauge jaw member comprising a surgical compression gaugeinstrument implemented with a retractable spacer member enables thesurgical compression gauge instrument to probe a tissue at thicknesslevel that cannot be accommodated by a compression gauge jaw member witha fixed height spacer member due to constraint on the height thereofimposed by the size of a trocar through which the surgical compressiongauge instrument must be inserted and withdrawn. Referring to FIG. 21showing a spacer assembly 140 and a cartridge body 31 comprising acompression gauge cartridge, broken away and sectioned apart, in anembodiment of the present invention, cartridge body 31 may be configuredto include a cavity 145 for housing a spacer assembly 140 comprising aspacer member 141, a stopper 142, a stopper control link 143,operatively joined with stopper 142, and a spacer spring 144. Cavity 145may comprise a spacer channel 146 disposed substantially perpendicularlyto tissue supporting surface 34 of cartridge body 31 with one end opento tissue supporting surface 34 for passage of spacer member 141 and theother end closed, and a stopper channel 147 disposed to intersect spacerchannel 146 substantially perpendicularly thereto in one end including apassage 148 for stopper control link 143 in the other end. Spacer member141 may be of rigid construction and configured to slidably engagespacer channel 146 to enable smooth and substantially precise movementalong the length of spacer channel 146. Stopper 142 may be configured toslidably engage stopper channel 147 to enable smooth and substantiallyprecise movement along the length of stopper channel 147. Disposed inspacer channel 146 between the closed end thereof and spacer member 141,spacer spring 144 may be configured to bias spacer member 141 to move inthe direction of the open end of spacer channel 146. Stopper 142 may bedriven by stopper control link 143 to position stopper 142 in, as shownin FIG. 22A, and out, as shown in FIG. 22B, of the path of spacer member141 in spacer channel 146. In an embodiment stopper 142 may beconfigured and constructed to provide a rigid stop to spacer member 141when positioned in the path thereof. Stopper control link 143 may beoperatively joined on the one end with stopper 142 and on the other endwith a mechanical or electronic control mechanism, preferably located onthe handle of a surgical stapler instrument or a surgical compressiongauge instrument, collectively referred to as the compression gaugeinstrument hereinafter, to be operated by the physician operator of thecompression gauge instrument. In the path of spacer member 141, as shownin FIG. 22A, stopper 142 rigidly holds spacer member 141 in positionextended above tissue supporting surface 34 of cartridge body 31 at apredetermined height maintaining a relative positional relationship ofthe two jaw members of end effector of the compression gauge instrumentclosed to compress a tissue captured there-between. Out of the path ofspacer member 141, as shown in FIG. 22B, stopper 142 allows spacermember 141 to be retracted to or below a height above tissue supportingsurface 34 of cartridge body 31 necessary for the two jaw members to beclosed sufficiently to allow the end effector of the compression gaugeinstrument to pass through a trocar.

In an embodiment of the present invention, as shown in FIG. 23A, stopper152 may comprise a plurality of steps 154, 155, each corresponding to apredetermined height of the spacer member above the tissue supportingsurface of the cartridge body. As show in FIG. 23B, in an exemplaryembodiment, spacer member 141 resting on step 155 may provide a smallergap distance between the two jaw members of end effector of thecompression gauge instrument and correspondingly a smaller compressedtissue thickness captured and compressed by the two jaw members. Asshown in FIG. 23C stopper 152 out of the path of spacer member 141,spacer member 141 may be retracted into the spacer channel to allowsufficient closure of the two jaw members for passage of the endeffector and withdrawal of the compression gauge instrument through atrocar. In an embodiment of the present invention, as shown in FIG. 24,stopper 162 may include a sloped face 164 that may allow the height ofthe spacer member above the tissue supporting surface of the cartridgebody to be varied continuously. In an exemplary embodiment, the stopperis depicted generally of a square block shape the stopper may be of anyother configuration. In an embodiment the spacer member and stopper maybe further configured to include an arrangement to stop the spacermember from being ejected clear out of the spacer channel by the spacerspring. In an alternate embodiment the cavity of the cartridge body maybe configured with an arrangement to stop the spacer member from beingejected clear out of the spacer channel by the spacer spring.

In an alternate embodiment of the present invention there is provided acompression gauge cartridge comprising a cartridge body configured toallow a spacer member to be extended to and held in position at apredetermined height above the tissue supporting surface of thecartridge body and retracted to or below the height required forinsertion and withdrawal through a trocar of the surgical staplerinstrument the end effector of which the compression gauge cartridge ismounted in. Referring to FIG. 25 showing a spacer assembly 170 and acartridge body 31 comprising a compression gauge cartridge, broken awayand sectioned apart, in an embodiment of the present invention,cartridge body 31 may be configured to include a cavity 175 for housinga spacer assembly 170 comprising a spacer member 171, a stopper 172, aspacer spring 173 and a stopper spring 174. Cavity 175 may comprise aspacer channel 176 disposed substantially perpendicularly to tissuesupporting surface 34 of cartridge body 31 with one end open to tissuesupporting surface 34 for passage of spacer member 171 and the other endclosed, and a stopper channel 177 disposed to intersect spacer channel176 substantially perpendicularly thereto in one end and closed in theother end. Spacer member 171 may be of rigid construction and configuredto slidably engage spacer channel 176 to enable smooth and substantiallyprecise movement along the length of spacer channel 176. Stopper 172 maybe configured to slidably engage stopper channel 177 to enable smoothand substantially precise movement along the length of stopper channel177. Disposed in spacer channel 176 between the closed end thereof andspacer member 171, spacer spring 173 may be configured to bias spacermember 171 to move in the direction of the open end of spacer channel176. Disposed in spacer channel 177 between the closed end thereof andstopper 172, stopper spring 174 may be configured to bias stopper 172 tomove in the direction of the open end of stopper channel 177 towardspacer channel 176 normally keeps stopper 172 in close contact withand/or in the path of spacer member 171 in spacer channel 176 as shownin FIG. 26A.

In an embodiment an interface 179 of stopper 172 with spacer member 171may be configured so that spacer member 171 traveling down spacerchannel 176 toward the closed end thereof, for example, driven byclosing action of the two jaw members of end effector of the compressiongauge instrument, causes stopper 172 to retract into stopper channel 177toward the closed end thereof as shown in FIG. 26B. Preferably, thestrength or spring constant of stopper spring 174 may be such that amagnitude of force required to be applied to stopper 172 by the anviljaw member to retract stopper 171 (referred to as a threshold forcehereinafter) is substantially higher than that of the reactionary loadfrom the compressed tissue between the two jaw members of thecompression gauge instrument to enable the physician operator operatingthe compression gauge instrument by the handle to sense that the two jawmembers reached a predetermined gap distance there-between correspondingto the height of spacer member 171. In the path of spacer member 171, asshown in FIG. 26A, stopper 172 substantially rigidly holds spacer member171 in position extended above tissue supporting surface 34 of cartridgebody 31 at a predetermined height maintaining relative positionalrelationship of the two jaw members of end effector of the compressiongauge instrument closed to compress a tissue captured there-between. Outof the path of spacer member 171, as shown in FIG. 26B, stopper 172allows spacer member 171 to be retracted to or below a height abovetissue supporting surface 34 of cartridge body 31 necessary for the twojaw members to be closed sufficiently to allow the end effector of thecompression gauge instrument to pass through a trocar. In an embodimentthe spacer member and stopper may be further configured to include anarrangement to stop the spacer member from being ejected clear out ofthe spacer channel by the spacer spring. In an alternate embodiment thecavity of the cartridge body may be configured with an arrangement tostop the spacer member from being ejected clear out of the spacerchannel by the spacer spring.

Referring to FIGS. 27 and 28A-28C showing spacer assemblies 180, 185 anda cartridge body 31 comprising a compression gauge cartridge, brokenaway and sectioned apart, in an embodiment of the present invention,cartridge body 31 may be configured to include a cavity 191 comprisingspacer channel 192 and stopper channel 193 for housing spacer assemblies180, 185, as described in the preceding in relation to FIGS. 25, 26A and26B, comprising a spacer members 181, 186, respectively. In anembodiment of the present invention spacer assemblies 180, 185 may be ofsubstantially rigid construction except spacer members 181, 186 that areconfigured to have different lengths along the length of spacer channel192 or different heights the difference of which corresponds todifference in the gap distance between the two jaw members separated byspacer members 181, 186 or corresponding difference in the tissuethicknesses captured and compressed by the two jaw members. In operationthe two jaw members are first held apart at a first predetermined gapdistance there-between by spacer member 181 as shown in FIG. 28A. Uponapplication of a first threshold force by the physician operator of thecompression gauge instrument stopper 182 and spacer member 181 retractand the jaw members are closed to and held apart at a secondpredetermined gap distance by spacer member 186 as shown in FIG. 28B.Upon further application of a second threshold force by the physicianoperator stopper 187 retracts and spacer members 181, 186 are free to beretracted for further closure of the two jaw members in preparation forwithdrawal of the compression gauge instrument through a trocar as shownin FIG. 28C.

Referring to FIG. 29 showing a spacer assembly 200 and a cartridge body31 comprising a compression gauge cartridge, broken away and sectionedapart and FIG. 30 showing spacer assembly in an exploded view, in anembodiment of the present invention, cartridge body 31 may be configuredto include a cavity 209 for housing spacer assembly 200 comprising aspacer member 201, a stopper stack 206 comprising at least one stopper207, operatively joined with a stopper control link 204, stacked on topof one another and a stopper spring 208, and a spacer spring 205. Cavity209 may comprise a spacer channel 210 disposed substantiallyperpendicularly to tissue supporting surface 34 of cartridge body 31with one end open to tissue supporting surface 34 for passage of spacermember 201, and a portion of the other end open to a stopper channel 211and the rest of the other end closed, and stopper channel 211 disposedto intersect spacer channel 210 substantially perpendicularly theretoclosed in one end that may include passages 212 for stopper control link204 in the other end. Spacer member 201 may be configured to slidablyengage spacer channel 210 to enable smooth and substantially precisemovement along the length of spacer channel 210. Stopper 207 may beconfigured to slidably engage stopper channel 211 to enable smooth andsubstantially precise movement along the length of stopper channel 211.Disposed in spacer channel 210 between the closed portion of the endthereof opposite tissue supporting surface 34 and spacer member 201,spacer spring 205 may be configured to bias spacer member 201 to move inthe direction of the open end of spacer channel 210. In an embodimentspacer member 201 may be of rigid construction and comprises a spacerbody 202 and a spacer stem 203 fixedly joined therewith facing theclosed end of spacer channel 210. In an embodiment stopper 207 may be ofsubstantially planar shape of a predetermined thickness and of rigidconstruction capable of supporting and substantially preciselymaintaining spacer member 201 in position under a load from the anviljaw member. Preferably the length of spacer stem 203 may be configuredto be equal to or longer the combined thickness of stoppers 207. Stopper207 comprises a through hole 209 dimensioned to receive spacer stem 203of spacer member 201 and, in an embodiment, at least one stoppers 207are stacked initially with through holes 209 aligned with one another.Sliding movement of stopper 207 in stopper channel 211 may be controlledby stopper control link 204 in similar fashion to how stopper 142 iscontrolled by stopper control link 143 as described previously referringto FIG. 21. In an embodiment stopper 207 may be biased by stopper spring208 to return to initial position, as described in FIG. 30 in anembodiment, following a control motion applied to stopper 207 by stoppercontrol link 204. In an embodiment operation of spacer assembly 200 isdescribed hereinafter referring to FIGS. 31A-31C. Initially, stoppers207 comprising stopper stack 206 may be disposed with through holes 209aligned with one another but not with spacer stem 203 of spacer member201 as shown in FIG. 31A rigidly supporting and holding spacer body 202in position at a predetermined vertical extent or height above thetissue supporting surface of the cartridge body even under a load fromthe anvil jaw member. In next step the physician operator operates onstopper control link 204 joined with the top most, i.e., the one incontact with spacer stem 203 of spacer member 201 to position throughhole 209 thereof to be aligned with spacer stem 203 as shown in FIG. 31Bin an embodiment. Under a load from the anvil jaw member spacer stem 203of spacer member 201 falls into through hole 209 of the top most stopper207 and spacer stem 203 now rests on the second to the top most stopper207 and the vertical extent or height thereof above the tissuesupporting surface of the cartridge body is reduced by the thickness ofthe top most stopper 207. In an embodiment similar operation by thephysician operator may be performed on the second to the top moststopper 207 to further reduce the vertical extent or height of spacerbody 202 above the tissue supporting surface of the cartridge body bythe thickness thereof as shown in FIG. 31C.

Referring to FIG. 32 showing a gap sensor 220 and a cartridge body 31comprising a compression gauge cartridge broken away and sectioned apartand FIG. 33 showing gap sensor 220 in an exploded view, in an embodimentof the present invention, cartridge body 31 may be configured to includea cavity 221 having at least one through hole 222 in the tissuesupporting surface of cartridge body 31 for housing gap sensor 220 forproviding an electrical signal indicative of the gap distance or angularpositional relationship between the two jaw members of end effector of asurgical stapler instrument instrumented with the compression gaugecartridge or a surgical compression gauge instrument. In an embodiment,as shown in detail in FIG. 33, gap sensor 220 may comprise a sensorhousing 213, made up of electrically conducting material, with a housingelectrode 215 attached thereto including at least one elongated chamber214, disposed substantially perpendicularly to the tissue supportingsurface of the cartridge body and having an opening substantiallyaligned with at least one through hole 222, for receiving a plungerassembly 216. In an embodiment plunger assembly 216 may comprise apiston 218, preferably configured to slidably engage elongated chamber214 to enable smooth and substantially precise movement along the lengththereof, a piston extension 217, a piston spring 219 and a pistonelectrode 223. As shown in FIG. 34, in an embodiment piston 218 may beconfigured to have an electrically conducting piston core 224 lined byan electrical insulation 225 along the perimeter thereof to electricallyisolate piston core 224 from sensor housing 213. In an embodiment pistonspring 219 is disposed between piston electrode 223 and piston 218 andconfigured to bias piston 218 in the direction of the tissue supportingsurface normally keeping piston core 224 of piston 218 in electricalcontact with sensor housing 213. Preferably, piston spring 219 may bemade of electrically conducting material in order to establish anelectrical connection between piston core 224 and piston electrode 223,and complete a circuit from housing electrode 215 to piston electrode223.

In an embodiment piston extension 217 may be configured to extend frompiston 218 passing through the opening in chamber 214 and at least onethrough hole 222 and protrude above the tissue supporting surface ofcartridge body 31 to a predetermined height, and constructed to besubstantially rigid to be able to conduct a load from the anvil jawmember to piston 218 as the two jaw members of the compression gaugeinstrument are being closed. Preferably, piston extension 217 may bemade of electrically non-conducting material to electrically isolatepiston core 224 from the anvil jaw member conventionally made of metal.As the closing anvil jaw member reaches and begins to depress pistonextension 217 piston core 224 detaches from housing 213 breaking offelectrical contact between housing electrode 215 and piston electrode223 generating an electrical signal in the form of broken electricalcontinuity just like an ordinary electrical switch being turned off.Preferably, the strength or spring constant of piston spring 219 may besuch that a magnitude of force required to be piston extension 217 bythe anvil jaw member to force piston 218 to retract is substantiallyhigher than that of the reactionary load from the compressed tissuebetween the two jaw members of the compression gauge instrument toenable the physician operator operating the compression gauge instrumentby the handle to sense that the two jaw members reached a predeterminedgap distance there-between corresponding to the height of pistonextension 217. The generated signal indicates that the two jaw membersreached a predetermined gap distance there-between corresponding to thepredetermined height of piston extension 217. In an embodiment there isprovided a gap sensor 220, capable of generating signals at a pluralityof predetermined gap distances between the two jaw members, comprising aplurality of piston assemblies 216 with piston extension 217 ofdifferent height from one another. It is to be understood that gapsensor 220 represents but one exemplary embodiment of a sensorconfiguration relying on electrical switching for sensing a gap distancebetween the two jaw members. Numerous other configurations of electricalswitch, well known to those of skill in the art, may be employed toconstruct a gap sensor for generating electrical signal indicative ofthe gap distance between the two jaw members. In an embodiment anelectrical switch gap sensor may be configured to generate signal in theform of established electrical continuity, i.e., just like an electricswitch being turned on. In an embodiment a gap sensor may be configuredto generate an electrical or electronic signal varying continuously tocorrespond to continuous change in the gap distance between the two jawmembers being closed. In an embodiment there is provided a processor forreceiving and processing a signal from a gap sensor and a signal fromthe force transducer comprising the compression gauge cartridge andproducing correlated set of data representative of gap distance andreactionary loads from the compressed tissue, and a display forpresenting the results. In an alternate embodiment the processor may befurther provided with capability to project a reactionary load at apredetermined gap distance, outside the capability of the compressiongauge instrument, based on the correlated data set and known mechanicalproperties of the subject tissue.

Referring to FIG. 35 showing in perspective view a gap sensor 230 and acartridge body 31 comprising a compression gauge cartridge broken awayand sectioned apart and FIG. 36 showing in perspective view gap sensor230 in detail, in an embodiment of the present invention, cartridge body31 may be configured to include a cavity 231 having a through hole 232in the tissue supporting surface of cartridge body 31, disposedsubstantially perpendicularly to the tissue supporting surface ofcartridge body 31, for housing gap sensor 230 for providing electricalsignals indicative of the gap distance or angular positionalrelationship between the two jaw members of end effector of a surgicalstapler instrument instrumented with the compression gauge cartridge ora surgical compression gauge instrument comprising a compression gaugejaw member comprising gap sensor 230. In an embodiment, as shown indetail in FIG. 36, gap sensor 230 may comprise a piston 233, made up ofelectrically conducting material and preferably configured to slidablyengage cavity 231 to enable smooth and substantially precise movementalong the length thereof, a piston spring 234, made up of electricallyconducting material, a piston electrode 235, and a piston extension 236,made up of electrically non-conducting or insulating material. There areprovided at least one sensor electrode 237, 238 disposed immediatelyadjacent to cavity 231 arranged such that piston 233 comes intoelectrical contact therewith during movement in cavity 231. In anembodiment piston spring 234 is disposed between piston electrode 235and piston 233 to provide an electrical contact there-between andconfigured to bias piston 233 in the direction of the tissue supportingsurface normally keeping piston 233 separated and electrically isolatedfrom sensor electrodes 237, 238. In an embodiment the position of thefirst point of contact of sensor electrode 237, disposed closest topiston 233, with piston 233 is predetermined, with piston extension 236of predetermined dimension in the direction of piston movement, tocorrespond to a first predetermined gap distance between the two jawmembers of a surgical stapler instrumented with the compression gaugecartridge or a surgical compression gauge instrument. In an embodimentthe distance between the first points of contact of two neighboringsensor electrodes is predetermined to correspond to incrementaldifference between two predetermined gap distances between the two jawmembers of a surgical stapler instrumented with the compression gaugecartridge or a surgical compression gauge instrument.

In an embodiment piston extension 236 may be configured to extend frompiston 233 passing through hole 232 and protrude above the tissuesupporting surface of cartridge body 31 to a predetermined height, andconstructed to be substantially rigid to be able to transfer a load fromthe anvil jaw member to piston 233 as the two jaw members of endeffector are being closed. Preferably, piston extension 236 may be madeof electrically non-conducting material to electrically isolate piston233 from the anvil jaw member conventionally made of metal. As theclosing anvil jaw member reaches and begins to depress piston extension236 piston 233 slides down cavity 231 to reach sensor electrode 237disposed closest to piston 233, with piston spring 234 in fully extendedposition, making electrical contact therewith and generating anelectrical signal in the form of electrical continuity between pistonelectrode 235 and sensor electrode 237 just like an ordinary electricalswitch being turned on. The generated signal indicates that the two jawmembers reached a first predetermined gap distance there-betweencorresponding to the position of the first point of contact of sensorelectrode 237. As the anvil jaw continues to close piston 233 reachessensor electrode 238, disposed second closest to piston 233, makingelectrical contact therewith and generating an electrical signal in theform of electrical continuity between piston electrode 235 and sensorelectrode 238. The generated signal indicates that the two jaw membersreached a second predetermined gap distance there-between correspondingto the position of the first point of contact of sensor electrode 238.

Referring to FIG. 37 showing in perspective view a gap sensor 240 and acartridge body 31 comprising a compression gauge cartridge broken awayand sectioned apart and FIG. 38 showing in perspective view gap sensor240 in detail, in an embodiment of the present invention, cartridge body31 may be configured to include a cavity 241 having a through hole 242in the tissue supporting surface of cartridge body 31, disposedsubstantially perpendicularly to the tissue supporting surface ofcartridge body 31, for housing gap sensor 240 for providing electricalsignal indicative of the gap distance or angular positional relationshipbetween the two jaw members of end effector of a surgical staplerinstrument instrumented with the compression gauge cartridge or asurgical compression gauge instrument comprising a compression gauge jawmember comprising gap sensor 240. In an embodiment, as shown in detailin FIG. 38, gap sensor 240 may comprise a force transducer 243 housed incavity 241 and a sensor spring 244 disposed to rest on the sensitivityor loading area of force transducer 243, where a load to be measuredneeds to be applied to, on the one end and to extend via through hole242 above the tissue supporting surface on the other end, which isconfigured to come in contact with and be depressed by the anvil jawmember as the two jaw members are closed. In an embodiment sensor spring244 may be calibrated to exert a load, to a predetermined precision, tothe loading area of force transducer 243 proportional to change inlength thereof occurring when depressed by the closing anvil jaw member.Preferably, there is provided a processor, to which the output signal offorce transducer 243 is connected to, which is configured to analyze theoutput signal and extract corresponding gap distance between the two jawmembers for display. In an embodiment sensor spring 244 may besubstituted with other elastic element calibrated to exert a load onforce transducer 243 proportional to change in a dimension thereofoccurring when depressed by the anvil jaw member.

Referring to FIG. 39 showing in perspective view a gap sensor 250 and acartridge body 31 comprising a compression gauge cartridge broken awayand sectioned apart and FIG. 40 showing in exploded view gap sensor 250in detail, in an embodiment of the present invention, cartridge body 31may be configured to include a cavity 251 including an elongated chamber252 with one end closed and the other open to the tissue supportingsurface of cartridge body 31 and disposed substantially perpendicularlyto the tissue supporting surface of cartridge body 31 for housing gapsensor 250 for providing electrical signals indicative of the gapdistance or angular positional relationship between the two jaw membersof end effector of a surgical stapler instrument instrumented with thecompression gauge cartridge or a surgical compression gauge instrumentcomprising a compression gauge jaw member comprising gap sensor 250. Inan embodiment, as shown in detail in FIG. 40, gap sensor 250 maycomprise a potentiometer 253, a transmission assembly 254, a pistonassembly 255 comprising a piston 256 of elongated and rigidconstruction, and a rack gear 257 fixedly joined with elongated piston256 substantially along the length thereof, and a piston spring 258.Preferably piston 256 may be configured to extend past the open end ofchamber 252 above the tissue supporting surface of cartridge body 31 toa predetermined extent sufficient to come in contact with the anvil jawmember at a predetermined gap distance between the two jaw members andto slidably engage chamber 252 to enable smooth and substantiallyprecise movement along the length thereof when depressed by the anviljaw member as the two jaw members are closed or urged by piston spring258 toward the anvil jaw member. Piston assembly 255 is biased by pistonspring 258, disposed in chamber 252 between the closed end thereof andpiston 256, to move in the direction of the open end of chamber 252. Inan embodiment transmission assembly 254 comprises a set of gearsincluding a pinion gear for engaging rack gear 257 for converting linearmotion of piston assembly 255 into a circular motion and a gearcombination for amplifying the motion of piston assembly 255 andtransferring the result of amplification in a rotary motion topotentiometer 253, well known to those of skill in the art, which isconfigured to convert an input rotary motion into an output voltagesignal of magnitude proportional to the degree of input rotary motion.Preferably, there is provided a processor, external to the compressiongauge cartridge or the surgical compression gauge instrument, forreceiving and processing the output voltage signal to provide an outputcorresponding to the distance travelled by piston assembly 255 fromwhich the gap distance between the two jaw members at any given point intime can be extracted.

Referring to FIG. 41 showing a compression gauge cartridge 261 and ananvil jaw member 262, having a tissue contacting surface 264, comprisingan end effector 260 of a surgical stapler instrument instrumented withcompression gauge cartridge 261 disposed in the cartridge bay of thecartridge jaw member thereof, in an embodiment of the present invention,a tissue supporting surface 263 of compression gauge cartridge 261 maybe configured to minimize compression of tissue captured between the twojaw members of end effector 260 outside the area covered by the tissuecompression face of the compression head comprising the force gaugeassembly comprising compression gauge cartridge 261 while tissuecontacting surface 264 of anvil jaw member 262 may be configured to besubstantially flat without special features thereon for reducing tissuecompression. Similarly, in an embodiment, a tissue supporting surface ofthe compression gauge jaw member of a surgical compression gaugeinstrument may be configured to minimize compression of tissue capturedbetween the two jaw members of end effector outside the area covered bythe tissue compression face of the compression head comprising the forcegauge assembly comprising the compression gauge jaw member while thetissue contacting surface of the anvil jaw member may be configured tobe substantially flat without special features thereon for reducingtissue compression. In an alternate embodiment, as shown in FIGS. 42Aand 42B, a tissue supporting surface 266 of compression gauge cartridge261 may be configured to be substantially flat without special featuresthereon for reducing tissue compression and tissue contacting surface264 of anvil jaw member 262 may be configured to include an anvilcompression head 265 of a predetermined shape configured to extend fromtissue contacting surface 264 of anvil jaw member 262 to minimizecompression of tissue captured between the two jaw members of endeffector 260 outside the area covered by the tissue compression face ofthe compression head. Preferably, the area over which anvil compressionhead 265 comes into contact with tissue is substantially equal to orlarger than that of the tissue compression face of the compression headcomprising the force gauge assembly comprising compression gaugecartridge 261. In another alternate embodiment, as shown in FIG. 43, atissue supporting surface 263 of compression gauge cartridge 261 may beconfigured to minimize compression of tissue captured between the twojaw members of end effector 260 outside the area covered by the tissuecompression face of the compression head and tissue contacting surface264 of anvil jaw member 262 may also be configured to include an anvilcompression head 267 of a predetermined shape configured to extend fromtissue contacting surface 264 of anvil jaw member 262 to minimizecompression of tissue captured between the two jaw members of endeffector 260. Preferably, the area over which anvil compression head 267comes into contact with tissue is substantially equal to or larger thanthe area of the tissue compression face of the compression headcomprising the force gauge assembly comprising compression gaugecartridge 261. In an embodiment of the present invention, as shown inFIG. 44, a spacer 273 may be disposed on anvil jaw member 272 and not oncompression gauge cartridge 271 comprising an end effector 270.Similarly, in an embodiment, a spacer may be disposed on the anvil jawmember and not on the compression gauge jaw member comprising an endeffector.

Referring to FIGS. 45A and 45 B showing in perspective view anadjustable and retractable spacer assembly 260 and a cartridge body 31comprising a compression gauge cartridge partially broken away andpartially broken away, sectioned and spaced apart, respectively, andFIG. 46 showing in perspective view spacer assembly 260 in detail, in anembodiment of the present invention, cartridge body 31 may be configuredto include a cavity 261 open to the tissue supporting surface ofcartridge body 31, disposed substantially perpendicularly to the tissuesupporting surface of cartridge body 31, for housing spacer assembly 260for providing a rigid stop for maintaining a predetermined gap distanceor angular positional relationship between the two jaw members of endeffector of a surgical stapler instrument instrumented with thecompression gauge cartridge or a surgical compression gauge instrumentcomprising a compression gauge jaw member comprising spacer assembly260. In an embodiment cavity 261 may be configured to slidably engagespacer assembly 260 to enable smooth and substantially precise movementof spacer assembly 260 therein substantially perpendicularly to thetissue supporting surface of cartridge body 31. In an embodiment, asshown in detail in FIG. 46, spacer assembly 260 may comprise a spacermember 264 of rigid construction having a threaded portion 265 of agender, a thumb wheel 266 having a through hole 267 with a matchingthread 268 of opposite gender to that of threaded portion 265 forreceiving spacer member 264 with threaded portion 265 rotatably engagingmatching thread 268 and a spacer spring 269. Preferably, thumb wheel 266may be configured to be partially exposed through a side 263 ofcartridge body 31 to allow manipulation by a physician operator.Preferably spacer member 264 may be configured to extend past theopening of cavity 261 above the tissue supporting surface of cartridgebody 31 to a predetermined extent sufficient to come in contact with theanvil jaw member at a predetermined gap distance between the two jawmembers and spacer spring 269 may be disposed to bias spacer assembly264 to move in the direction of the opening of cavity 261. In anembodiment the distance above the tissue supporting surface spacermember 264 extends may be adjusted by turning thumb wheel 266 whichdrives spacer member 264 up and down cavity 261 via the rotatable,threaded engagement between thumb wheel 266 and spacer member 264. Whenspacer member 264 is depressed by the anvil jaw member as the two jawmembers are closed or urged by spacer spring 269 toward the anvil jawmember spacer assembly 260 moves along cavity 261 smoothly andsubstantially precisely allowing spacer assembly 260 to be retractedinto cavity 261, preferably, sufficiently for the two jaw memberscomprising end effector to be closed and be able to pass through atrocar. Preferably, the strength or spring constant of spacer spring 269may be such that a magnitude of force required to be applied to spacermember 264 by the anvil jaw member to cause spacer assembly 260 toretract is substantially higher than that of the reactionary load fromthe compressed tissue between the two jaw members of the compressiongauge instrument to enable the physician operator to be able sense thatthe two jaw members reached a predetermined gap distance correspondingto the extent or height of spacer member 264 above the tissue supportingsurface of cartridge boy 31.

In an embodiment of the present invention there is provided a surgicalinstrument with an end effector comprising a pair of jaw memberspivotally engaged with each other through a pivot mechanism, which openand close when driven by a drive mechanism associated with handleoperated by a physician, for example, to capture a tissue there-between,with one of the jaw members instrumented with a spacer assemblycomprising a spacer member and a base or a spacer base for maintaining apredetermined gap distance or relative angular positional relationshipbetween the two jaw members when the two jaw members are closed. In anembodiment one of the two jaw members comprising the end effector of thesurgical instrument may be an anvil jaw member and the other acompression gauge jaw member comprising a spacer assembly and a forcegauge assembly comprising a force transducer and a compression head. Thesurgical instrument may further comprise a mechanism for controlling theposition of the spacer base that may be operated by a physician toselect the gap distance between the two jaw members.

Referring to FIGS. 47 and 48 showing, in an embodiment of the presentinvention, a surgical instrument 300 in perspective view and a surgicalinstrument partially sectioned and spaced apart, respectively, for usein a surgical operation, surgical instrument 300 may comprise a handle301, an elongated shaft 302 extending distally from handle 301 andhaving a proximal end and a distal end, an end effector 303 supported byelongated shaft 302 at distal end thereof and comprising a pair of jawmembers 303 a, 303 b pivotally engaged with each other, a spacer basecontrol mechanism or a base control mechanism 304, and a signalprocessor and display unit 305 disposed proximally to handle 301 and atthe proximal end of elongated shaft 302. In an embodiment of the presentinvention one of the two jaw members 303 a, 303 b may be configured as acompression gauge jaw member instrumented with a force gauge assemblyand a spacer assembly, and the other jaw member 303 b may be configuredas an anvil jaw member. In an embodiment the surgical instrument mayfurther comprise a rotation wheel 306 fixedly joined coaxially withelongated shaft 302 and elongated shaft 302 may be configured to rotatewith respect to handle 301 so that a physician may rotate elongatedshaft 302 along with end effector 303, spacer base control mechanism 304and signal processor and display unit 305 about the axis or the lengthdirection of elongated shaft 302 to aid in application of the surgicalinstrument. In an embodiment elongated shaft 302 may comprise a bendablesection operably connected with a bending control mechanism in handle301 to allow articulation of end effector 303 to aid in application ofthe surgical instrument. As shown in FIG. 48 and in detail in FIG. 49 inan embodiment of the present invention end effector 303 may be operablyconnected with handle 301 by an end effector control link 307 disposedin elongated shaft 302, which transfers the actuation force applied tohandle 301 by a physician or a power driven actuator (see FIG. 65) inoperating handle 301 to open or close the two jaw members 303 a, 303 bcomprising end effector 303. As shown in FIG. 48 and in detail in FIG.50 in an embodiment of the present invention spacer base controlmechanism 304 may be operably connected with a spacer base 313comprising a spacer assembly (for example, see FIGS. 54-56) by a spacerbase control link 308 disposed in elongated shaft 302, which transfersthe actuation force applied to spacer base control mechanism 304 by aphysician or a power driven actuator (see FIG. 65) in operating spacerbase control mechanism 304 to manipulate the position of spacer base313. In an embodiment spacer base control mechanism 304 includes a guidemember 310 for guiding spacer base control link 308. Detaileddescriptions of various embodiments of spacer base control mechanism areprovided later in this Detailed Description. As shown in FIG. 50 and indetail in FIG. 51, in an embodiment of the present invention, signalprocessor and display unit 305 comprises a display screen 312 and anelectronic circuit board 311 which may be electrically connected with aforce transducer 314 by a signal cable including a plurality ofconductors or electrical lines for receiving output signals from andsupplying power needed in operating force transducer 314. In anembodiment electronic circuit board 311 may be configured to accommodatevarious electronic components including a signal processor or CPUrequired to process output signals from force transducer 314 and todrive display screen 312, and to control power driven actuators foroperating handle 301 and/or spacer base control mechanism 304 (see FIG.65). In an embodiment the CPU may display various information producedin the course of signal processing and power driven actuator control ondisplay screen 312 and/or on a remote display screen, for example, viawireless link. In an embodiment an electrical power needed in operatingelectronic circuit board 311 may be housed signal processor and displayunit 305 in the form of one or more batteries. In an alternateembodiment an electrical power may be supplied from an external powersource (not shown in the FIGURES).

Referring to FIGS. 52 and 53 showing, in an alternate embodiment of thepresent invention, a surgical instrument 300 in perspective view and asurgical instrument partially sectioned and spaced apart, respectively,for use in a surgical operation, surgical instrument 300 may comprise aspacer base control mechanism 315 disposed distally to handle 301 andhaving a boss 316 for fixedly attaching spacer base control link 308,and a signal processor and display unit 305 associated with handle 301.In an embodiment spacer base control mechanism 315 may be configured asa collar slidably disposed along and around elongated shaft 302 disposedat a predetermined position along the length thereof. In FIGS. 52 and 53the same reference characters are used as in FIGS. 47-51 to identifylike elements. In an embodiment a physician operates spacer base controlmechanism 315 by sliding back and forth along the length of elongatedshaft 302 to impart a linear driving force to spacer base control link308. In an embodiment the surgical instrument may further comprise arotation wheel fixedly joined coaxially with elongated shaft 302 andelongated shaft 302 may be configured to rotate with respect to handle301 so that a physician may rotate elongated shaft 302 along with endeffector 303 and spacer base control mechanism 304 about the axis or thelength direction of elongated shaft 302 to aid in application of thesurgical instrument.

In a practical implementation of a spacer assembly described previouslywith reference to FIGS. 21-24, FIG. 54 shows, in perspective view, aspacer assembly 321 disposed in a compression gauge jaw member 303 a,shown partially broken, sectioned and spaced apart, comprising an endeffector comprising a surgical instrument in an embodiment of thepresent invention, and FIG. 55 shows, in perspective view, spacerassembly 321 in detail. As shown in FIG. 54, in an embodiment,compression gauge jaw member 303 a may be configured to include a cavity322 open to a tissue supporting surface 323 thereof for housing spacerassembly 321 for providing a rigid stop top to maintain a predeterminedgap distance or angular positional relationship between the anvil andcompression gauge jaw members comprising the end effector. In anembodiment, as shown in detail in FIG. 55, spacer assembly 321 maycomprise a spacer member 325 of rigid construction, a spacer base 326,referred to as a stopper in describing FIGS. 21-24, of rigidconstruction operatively joined with spacer base control link 308 andconfigured to support spacer member 325 on a stepped side 327 thereofwith each step corresponding to a discrete height of spacer member 325above tissue supporting surface 323 of jaw member 303 a, and spacersprings 328. In an alternate embodiment, as shown in FIG. 56, spacerbase 331 may be configured to support spacer member 330 on a sloped side332 to allow the height of spacer member 325 above tissue supportingsurface 323 of jaw member 303 a to be varied continuously. In anembodiment of the present invention spacer member 325, 330 and cavity322 may be configured to allow spacer member 325, 330 to move smoothlyand substantially precisely in direction substantially perpendicular totissue supporting surface 323 of jaw member 303 a and spacer base 326,331 and cavity 322 may be configured to allow spacer base 326, 331 tomove smoothly in direction substantially perpendicular to spacer member325, 330 and parallel to tissue supporting surface 323 of jaw member 303a. In an embodiment spacer springs 328 are configured to bias spacermember 325, 330 toward the anvil jaw member (not shown in FIG. 54). Inan embodiment spacer base control link 308 may be directly joined withand configured to transfer a linear actuation force provided by a spacerbase control mechanism to drive spacer base 326, 331 to move back andforth substantially linearly and parallel to tissue supporting surface323 of jaw member 303 a to change the position of spacer base 326 withrespect to spacer member 325. In an alternate embodiment spacer basecontrol link 308 may be operably joined with spacer base 326, 331 via amotion conversion means to convert, for example, an actuation forcetransferred via spacer base control link 308 from rotation to linearform, to drive spacer base 326, 331 to move back and forth substantiallyparallel to tissue supporting surface 323 of jaw member 303 a. In anembodiment spacer assembly 321 may include a spring for biasing spacerbase 326, 331 toward or away from spacer base control link 308. Spacerassemblies shown in FIG. 12A and FIGS. 45B and 46 are some of exemplaryembodiments of spacer assembly requiring a rotation of a spacer base toadjust the height of the spacer member above the tissue supportingsurface of a jaw member in which the spacer assembly is housed. Spacerassembly shown in FIGS. 29 and 31C is an exemplary embodiment of spacerassembly requiring a plurality of spacer base control links to adjustthe height of the spacer member above the tissue supporting surface of ajaw member in which the spacer assembly is housed.

Referring to FIGS. 57 and 50, in an embodiment of the present invention,spacer base control link 308, having a proximal end 335 and a distal end336, may be of any configuration and construction suitable for transferof actuation force imparted thereto by a spacer base control mechanism304, which will be described later in this Detailed Description. In anembodiment spacer base control link 308 may comprise at least oneflexible wire, at least one rigid rod, at least one hydraulic orpneumatic line, at least one threaded rod, at least one rigid bar, atleast one bar flexible lengthwise or a combination thereof with proximaland distal end 335, 336 of spacer base control link 308 configured tooperably engage a spacer base control mechanism and a spacer base,respectively. For example, in an embodiment, proximal end 335 of spacerbase control link 308 may be configured or terminated with a camfollower 337 to operably engage a spacer base control mechanism based ona cam driving mechanism, for example, as illustrated in FIG. 59. In anembodiment distal end 336 may be terminated with a force conversionmechanism before being operably joined with a spacer base including ascrew on a threaded shaft, a worm gear drive, a rack and pinion gears, acrank mechanism or a cam drive mechanism to convert a linear actuationforce transferred via spacer base control link 308 to a rotationalactuation force and vice versa, which is then applied to the spacerbase. In an embodiment actuation force provided by a spacer base controlmechanism that may be transferred by spacer base control link 308 mayinclude a linear force, i.e., push and/or pull force, a rotational forceor a fluid pressure. As shown in FIG. 58 spacer base control link 340may comprise a core link element 341, for example, a flexible wire, arigid rod, a threaded rod, a rigid bar, a bar flexible lengthwise housedin a tubular housing 342. Preferably, tubular housing 342 may beconstructed to be able to maintain a constant length with two endsthereof fixedly joined with a spacer base control mechanism and a jawmember instrumented with a spacer assembly, for example, a compressiongauge jaw member, respectively. In an embodiment tubular housing 342 maybe flexible so that spacer base control link 340 may be used in anelongated shaft with a bendable section comprising the surgicalinstrument of the present invention. In an alternate embodiment tubularhousing 342 may be rigid.

Referring to FIG. 59 showing in perspective view a spacer base controlmechanism 345 based on a cam drive mechanism, sectioned and spacedapart, in an embodiment of the present invention, spacer base controlmechanism 345 may comprise a thumbwheel 346 having a rotation axis 348disposed substantially perpendicularly to the length direction of spacerbase control link 308 and a cam groove 347 configured to receive a camfollower 349 of spacer base control link 308. In an embodiment camgroove 347 may be designed in such a way that rotation of thumbwheel 345drives cam follower 349 linearly along the length of spacer base controllink 308, which may be guided by guide member 310 as shown in FIG. 50.In an embodiment cam groove 347 may be designed to apply a pull force tospacer base control link 308 when rotated in a predetermined direction.In an embodiment cam groove 347 may be designed to apply a pull force tospacer base control link 308 when rotated in a predetermined directionand a push force in opposite direction. Referring to FIG. 60 showing inperspective view a spacer base control mechanism 350 based on aslider-crank mechanism, sectioned and spaced apart, in an alternateembodiment of the present invention, spacer base control mechanism 350may comprise a thumbwheel 351 having a rotation axis 354 disposedsubstantially perpendicularly to the length direction of spacer basecontrol link 308 and a crank 353 pivotally joined with a pivot 352disposed on thumbwheel 351 on one end and spacer base control link 308on the other end. In an embodiment pivot 352 may be disposed onthumbwheel 351 in such a way that rotation of thumbwheel 351 drivesspacer base control link 308 linearly along the length thereof. In anembodiment pivot 352 may be disposed to apply a pull force to spacerbase control link 308 when rotated in a predetermined direction. In anembodiment pivot 352 may be disposed to apply a pull force to spacerbase control link 308 when rotated in a predetermined direction and apush force in opposite direction. Referring to FIG. 61 showing inperspective view a spacer base control mechanism 355 based on a rack andpinion gears, in an alternate embodiment of the present invention,spacer base control mechanism 355 may comprise a thumbwheel 356 having arotation axis 359 disposed substantially perpendicularly to the lengthdirection of spacer base control link 308, a pinion gear 385 disposedcoaxially with rotation axis 359 and a rack gear 357 fixedly joined withspacer base control link 308. Spacer base control mechanism 355 iscapable of providing a pull and push force to spacer base control link308 depending on the direction of rotation of thumbwheel 356 effectivelyconverting rotational actuation force to linear actuation force.

Referring to FIG. 62 showing in perspective view a spacer base controlmechanism 360 based on a thumbwheel drive, in an embodiment of thepresent invention, spacer base control mechanism 360 may comprise athumbwheel 361 with rotation axis disposed substantially in line withthe length direction of spacer base control link 308 fixedly joinedtherewith. Rotation of thumbwheel 361 directly imparts a rotationactuation force to spacer base control link 308. Referring to FIG. 63showing in perspective view a spacer base control mechanism 365 based ona screw drive, in an embodiment of the present invention, spacer basecontrol mechanism 365 may comprise a thumbwheel 366 with rotation axisdisposed substantially in line with the length direction of spacer basecontrol link 308 and a threaded hole disposed coaxially therewith. In anembodiment spacer base control link 308 may be terminated with athreaded rod end 367 with thread matching that of thread hole inthumbwheel 366 to be mated therewith. Rotation of thumbwheel 366 causesa linear motion of spacer base control link 308 through threaded rod end367. Referring to FIG. 64 showing in perspective view a spacer basecontrol mechanism 370 based on a worm drive, in an embodiment of thepresent invention, spacer base control mechanism 370 may comprise a worm372 and a worm gear 371 with rotation axis disposed in line with spacerbase control link 308. Rotation of worm 372 causes worm gear 371 torotate rotationally driving spacer base control link 308.

Referring to FIG. 65 showing, in an embodiment of the present invention,a surgical instrument 375 in perspective view, partially sectioned andspaced apart, for use in a surgical operation, surgical instrument 375may comprise a handle 376, an elongated shaft 377 extending distallyfrom handle 376 and having a proximal end and a distal end, an endeffector (not shown in FIG. 65) supported by elongated shaft 377 atdistal end thereof and controlled by end effector control link 307configured to be driven by powered actuators, for example, by electricalmotor, a spacer base control mechanism 378 configured to be driven bypowered actuators, for example, by electrical motor to actuate spacerbase control link 308, and a signal processor and display unit 379. Inan embodiment of the present invention the powered actuators driving endeffector control link 307 and spacer base control link 308 may becontrolled by the CPU housed in signal processor and display unit 379,which also may process output signals from the force transducer from acompression gauge jaw member instrumented therewith and drive thedisplay screen. In an embodiment signal processor and display unit 379may be provided with programmable capabilities to coordinate controls ofthe end effector and the spacer base comprising the spacer base assemblywith the results of processing of output signals from the forcetransducer.

Any patent, publication, or other disclosure material, in whole or inpart, that is said to be incorporated by reference herein isincorporated herein only to the extent that the incorporated materialsdoes not conflict with existing definitions, statements, or otherdisclosure material set forth in this disclosure. As such, and to theextent necessary, the disclosure as explicitly set forth hereinsupersedes any conflicting material incorporated herein by reference.Any material, or portion thereof, that is said to be incorporated byreference herein, but which conflicts with existing definitions,statements, or other disclosure material set forth herein will only beincorporated to the extent that no conflict arises between thatincorporated material and the existing disclosure material.

While preferred illustrative embodiments of the invention are describedabove, it will be apparent to those skilled in the art that variouschanges and modifications may be made therein without departing from theinvention. Accordingly, the appended claims should be used to interpretthe scope of the present invention.

What is claimed is:
 1. A surgical instrument for assessing a mechanicalproperty of tissue under compression comprising: a handle; an elongatedshaft disposed distally and operably coupled to said handle; an endeffector disposed distally and operably coupled to said elongated shaft,said end effector comprising: a first jaw member and a second jaw memberpivotally joined for pivotal motion with respect to each other to openand close when operated by said handle to capture and compress saidtissue there-between; an adjustable spacer assembly comprising anadjustable spacer member and a spacer base disposed on said first jawmember; a control mechanism supported by said elongated shaft anddisposed adjacent to said handle for producing an actuation force; andat least one control link having a first end and a second end, disposedin said elongated shaft operably engaged with said control mechanism andsaid spacer base comprising said adjustable spacer assembly andconfigured to transmit said actuation force.
 2. A surgical instrument ofclaim 1, wherein said first jaw member comprises a compression gauge jawmember instrumented with a force gauge assembly comprising a compressionhead and a force transducer, and said second jaw member comprises ananvil jaw member.
 3. A surgical instrument of claim 1, wherein saidsurgical instrument further comprises a signal processor and displayunit.
 4. A surgical instrument of claim 1, wherein said at least onecontrol link is operably joined with said control mechanism at saidfirst end and said spacer base comprising said adjustable spacerassembly at said second end.
 5. A surgical instrument of claim 4,wherein said at least one control link is configured to transmit alinear actuation force.
 6. A surgical instrument of claim 4, whereinsaid at least one control link is configured to transmit a rotationalactuation force.
 7. A surgical instrument of claim 1, wherein said atleast one control link is selected from the group including a wire, arigid rod, a fluid line, a threaded rod, a rigid bar and a bar flexiblelengthwise.
 8. A surgical instrument of claim 7, wherein said at leastone control link further comprises a tubular housing.
 9. A surgicalinstrument of claim 1, wherein said at least one control link isterminated at said second end with a force conversion mechanism selectedfrom the group including a screw on a threaded shaft, a worm gear drive,a rack and pinion gears, a crank mechanism and a cam drive mechanism toconvert a linear actuation force to a rotation actuation force, viceversa, which is operably joined with said spacer base.
 10. A surgicalinstrument of claim 1, wherein said at least one control link comprisesa cam follower disposed at said first end and said control mechanismcomprises a cam drive mechanism comprising a thumbwheel comprising a camgroove configured to receive said cam follower.
 11. A surgicalinstrument of claim 10, wherein said thumbwheel comprising said controlmechanism produces a pull force on said at least one control link whenrotated in one direction and a push force when rotated in the otherdirection.
 12. A surgical instrument of claim 1, wherein said controlmechanism comprises a slider-crank mechanism comprising a thumbwheel anda crank pivotally joined with a pivot disposed on said thumbwheel on oneend and said at least one control link on the other end.
 13. A surgicalinstrument of claim 12, wherein said thumbwheel comprising said controlmechanism produces a pull force on said at least one control link whenrotated in one direction and a push force when rotated in the otherdirection.
 14. A surgical instrument of claim 1, wherein said controlmechanism comprises a rack-and-pinion gear mechanism comprising athumbwheel, a pinion gear and a rack gear fixedly joined with said atleast one control link.
 15. A surgical instrument of claim 14, whereinsaid thumbwheel comprising said control mechanism produces a pull forceon said at least one control link when rotated in one direction and apush force when rotated in the other direction.
 16. A surgicalinstrument of claim 1, wherein said control mechanism comprises athumbwheel drive mechanism comprising a thumbwheel coaxially joined withsaid at least one control link.
 17. A surgical instrument of claim 1,wherein said at least one control link comprises a threaded rod disposedat said first end and said control mechanism comprises a screw drivemechanism comprising a thumbwheel having a threaded hole coaxiallydisposed therewith configured to receive said threaded rod comprisingsaid at least one control link.
 18. A surgical instrument of claim 1,wherein said control mechanism comprises a worm drive mechanismcomprising a worm and a worm gear whose rotation axis is fixedly joinedwith said at least one control link.
 19. A surgical instrumentcomprising: a handle; an elongated shaft disposed distally and operablycoupled to said handle; an end effector disposed distally and operablycoupled to said elongated shaft, said end effector comprising: a firstjaw member and a second jaw member pivotally joined for pivotal motionwith respect to each other to capture and compress a tissuethere-between, and configured to open and close when operated by saidhandle; an adjustable spacer assembly comprising an adjustable spacermember and a spacer base disposed on said first jaw member; an actuationmechanism supported by said elongated shaft and disposed adjacent tosaid handle for producing an actuation force for controlling saidadjustable spacer assembly; and at least one force transmissionmechanism disposed in said elongated shaft operably engaged with saidactuation mechanism and said spacer base comprising said adjustablespacer assembly, and configured to transmit said actuation force.